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Biomedical subjects

A Shotan

Publications and source records attributed to A Shotan.

At least 37 records · Page 2Linked to original sources
PubMed1995

Cardiovascular problems in pregnant women with the Marfan syndrome.

PURPOSE: To review the available information on the diagnostic, prognostic, and therapeutic aspects of cardiac complications in women with the Marfan syndrome during the peripartum period and to develop guidelines for the approach to these patients on the basis of this information. DATA SOURCES: A MEDLINE search and a manual search of bibliographies from reviewed articles. STUDY SELECTION AND DATA EXTRACTION: Articles that reported on pregnancy in patients with the Marfan syndrome or that discussed potentially relevant aspects of the syndrome. RESULTS: Pregnancy in the Marfan syndrome is associated with two primary problems: potential catastrophic aortic dissection and the risk for having a child with the syndrome. The risk for peripartum aortic dissection is especially high in women in whom aortic root dilatation is diagnosed before pregnancy. Gestation seems to be safer in women without preexisting cardiovascular disease; however, an event-free pregnancy cannot be guaranteed. The Marfan syndrome is inherited in an autosomal dominant manner, and the fetus has a 50% risk for inheriting the mutant gene. CONCLUSIONS: Women with the syndrome should be counseled before conception about the risks of pregnancy to both mother and fetus. Because preconceptual dilatation of the ascending aorta seems to be an important predictor for aortic dissection, it should be excluded before pregnancy. Transesophageal echocardiography seems to be preferable for noninvasive assessment of aortic dilatation before and during pregnancy. Prophylactic use of beta-blockers may be useful in preventing aortic dilatation. Surgery should be considered during gestation in patients with progressive aortic dilatation when or before the aortic root reaches 5.5 cm. Because of the potential risk of ionizing radiation to the fetus, noninvasive methods such as transesophageal echocardiography and magnetic resonance imaging are preferred to contrast aortography for the diagnosis of aortic dissection during pregnancy. Vaginal delivery can be done in patients with the Marfan syndrome who do not have cardiovascular system abnormalities. In patients with aortic dilatation, aortic dissection, or other important cardiac abnormalities, cesarean section should be the preferred method of delivery.

Delivery, Obstetric↗
PubMed1995

Escalating nitrate dose overcomes early attenuation of hemodynamic effect caused by nitrate tolerance in patients with heart failure.

This study was performed to examine the hypothesis that an early attenuation of nitrate effect caused by nitrate tolerance can be overcome by dose increase. We compared hemodynamic effects of constant dose (40 to 120 mg) of oral isosorbide dinitrate (ISDN) given every 6 hours for three doses followed by 12 hours of nitrate washout interval with those of escalating dose (40 mg, 80 mg, and 120 mg) in two similar groups of patients with chronic congestive heart failure. Escalating ISDN dose resulted in a progressive increase in ISDN blood level and overcame early attenuation of effect occurring with a constant dose. At peak effect of the third ISDN dose, a significantly greater reduction was seen in mean right atrial pressure (-59% +/- 27% vs -20% +/- 22%, p < 0.01), mean pulmonary artery pressure (-29% +/- 11% vs -11% +/- 15%, p < 0.01) and mean pulmonary artery wedge pressure (-39% +/- 19% vs -19% +/- 23%, p < 0.05) with the escalating dose. These findings demonstrate that early attenuation of hemodynamic effect caused by nitrate tolerance can be overcome by dose escalation.

Adult↗
PubMed1995

Asymptomatic hyperglycemia in coronary heart disease: frequency and associated lipid and lipoprotein levels in the bezafibrate infarction prevention (BIP) register. The BIP Study Group.

BACKGROUND: The lipid profile of patients with type-II diabetes is characterized by low levels of high-density lipoprotein cholesterol, hypertriglyceridemia, and increased levels of lipoprotein (a), all of which may affect the prognosis in patients with atherosclerotic cardiovascular disease. This study aimed to assess the prevalence of asymptomatic hyperglycemia and the associated lipid profile in a large group of patients with documented coronary heart disease. METHODS: From February 1990 to October 1992, 14,326 patients aged 45-74 years with documented coronary heart disease (a history of myocardial infarction or angina pectoris) were screened for inclusion in a secondary prevention study using bezafibrate retard. All screened patients underwent a medical examination and a blood test after fasting for 14 h. Asymptomatic hyperglycemia was defined as a fasting blood glucose level of 140 mg/dl or above in patients with no previous history of diabetes mellitus. RESULTS: The prevalence of asymptomatic hyperglycemia was 4%, with no differences between the sexes or age groups. Total cholesterol and triglyceride levels were significantly higher and the high-density lipoprotein cholesterol level significantly lower in asymptomatic hyperglycemic than in normoglycemic patients. After multiple adjustments, the relative risk of death was 1.75 and 1.71 in patients with diabetes or asymptomatic hyperglycemia compared with those with no glycemic disorders. CONCLUSION: Asymptomatic hyperglycemia was detected in 4% of patients with ischemic heart disease. The lipid profile in these 4% resembles that of patients with confirmed diabetes, and their morbidity and mortality may therefore be higher than that of normoglycemic patients. Repeated assessment of glucose levels in patients with coronary heart disease is mandatory.

Aged↗
PubMed1995

Effects of brief and prolonged ischemia on eicosanoid synthesis in dog and rat hearts.

We compared the effects of brief and prolonged myocardial ischemia on tissue prostaglandin synthesis. Regional ischemia was induced in dogs and maintained for 5 or 30 minutes. Isolated rat hearts were subjected to global ischemia in a working heart preparation for periods of 5 or 20 minutes. De novo synthesis of prostaglandins PGE2 and PGF2 alpha was measured in endocardial and epicardial explants from hearts subjected to transient ischemia. After 5 minutes of coronary ligation, PGE2 production by the ischemic canine endocardium increased by 68%, compared with non-ischemic tissue, and PGF2 alpha levels rose by 29%. In isolated rat hearts, 5-minute ischemia increased endocardial rate of PGE2 synthesis (13.2 +/- 1.7 pmol/g/h, as compared with 6.7 +/- 0.5 under normoxic conditions). Ischemic stimulation of eicosanoid production by the endocardium was no longer apparent after 30-minute regional or 20-minute global ischemia. In contrast, the epicardium showed significant changes only after 30-minute ischemia and only with respect to PGF2 alpha (12.0 +/- 6.2 in the ischemic vs 7.1 +/- 3.2 pmol/g/h in the non-ischemic tissue). Ischemia-induced differences in prostaglandin production were attenuated in the presence of arachidonic acid or aspirin.

Animals↗
PubMed1994

Risks of angiotensin-converting enzyme inhibition during pregnancy: experimental and clinical evidence, potential mechanisms, and recommendations for use.

OBJECTIVE: To review reports on the use of angiotensin-converting enzyme inhibitors (ACE-I) during pregnancy in order to determine the incidence, nature, and potential mechanisms of fetal complications in an attempt to establish recommendations related to the use of these drugs during gestation. DATA SOURCES: Relevant English-language articles identified through a Medline search and bibliographies found in recent articles. STUDY SELECTION: Large number of reports both on animals and on humans have consistently shown a high degree of morbidity and even mortality in fetuses or newborns exposed to ACE-I during pregnancy. The reported complications include oligohydramnios, intrauterine growth retardation, premature labor, fetal and neonatal renal failure, bony malformations, limb contractures, persistent patent ductus arteriosus, pulmonary hypoplasia, respiratory distress syndrome, prolonged hypotension, and neonatal death. A high incidence of fetal complications was related to the use of ACE-I at all trimesters of pregnancy. CONCLUSION: The gestational use of ACE-I may be associated with a high degree of fetal and newborn morbidity and even mortality. The use of these drugs should be avoided at all trimesters of pregnancy.

Abnormalities, Drug-Induced↗
PubMed1994

Potentiation of isosorbide dinitrate effects with N-acetylcysteine in patients with chronic heart failure.

BACKGROUND: Supply of sulfhydryl groups with the administration of N-acetylcysteine (NAC) has been reported to reverse tolerance to nitroglycerin but not to isosorbide dinitrate (ISDN). Lack of interaction between NAC and ISDN was suggested as an explanation for these findings. The present study was therefore designed to further evaluate this hypothesis. For this purpose, we compared the hemodynamic and hormonal effects of ISDN when given alone and in combination with NAC. METHODS AND RESULTS: We performed a randomized, cross-over design evaluation of the hemodynamic and hormonal effects of ISDN and ISDN + NAC in 14 patients with chronic congestive heart failure due to left ventricular systolic dysfunction. The findings of this study demonstrated a substantial NAC-mediated potentiation of ISDN effect on mean right atrial pressure (-11 +/- 21% versus -38 +/- 27%, -17 +/- 20% versus -34 +/- 27%, and -7 +/- 20% versus -25 +/- 26% at 2, 3, and 4 hours, respectively; all P < .05), mean pulmonary artery wedge pressure (-18 +/- 16% versus -33 +/- 14%, -15 +/- 25% versus -33 +/- 19%, -14 +/- 22% versus -25 +/- 22%, and -16 +/- 16% versus -26 +/- 16% at 2, 3, 4, and 5 hours, respectively; all P < .05), mean pulmonary artery pressure (-8 +/- 11% versus -20 +/- 15% at 3 hours, P < .05), and cardiac output (an increase of 2 +/- 16% versus 25 +/- 20% at 4 hours, P < .05). Although there were no significant changes in serum catecholamine levels and plasma renin concentration with both regimens, ISDN + NAC resulted in a greater fall in plasma levels of atrial natriuretic peptide (296 +/- 251 pg/mL after ISDN versus 202 +/- 118 pg/mL after ISDN + NAC, P < .05). CONCLUSIONS: The results of this study provide strong evidence for the existence of an interaction between thiols and ISDN and further support the role of sulfhydryl groups in the activation and therapeutic action of organic nitrates. The discrepancy between the results of this study demonstrating NAC-induced potentiation of ISDN effects and a previous study showing failure to reverse ISDN tolerance with NAC may suggest that ISDN-NAC interaction requires normal intracellular levels of sulfhydryl groups and does not occur after intracellular sulfhydryl group depletion.

Acetylcysteine↗
PubMed1993

A randomized comparison between the hemodynamic effects of hydralazine and nitroglycerin alone and in combination at rest and during isometric exercise in patients with chronic mitral regurgitation.

Both arteriolar vasodilation with hydralazine and venodilation with nitroglycerin have been shown to favorably alter the hemodynamic profile in patients with chronic mitral regurgitation. Since these therapeutic modalities exert their effects by different mechanisms, this study was designed to assess hemodynamic response to both drugs given individually and in combination at rest and during isometric exercise in patients with chronic mitral regurgitation of various etiologies. When used individually, hydralazine caused larger increase in heart rate, cardiac index, stroke volume index, and systemic vascular resistance both at rest and during exercise. In contrast, nitroglycerin administration was associated with a superior effect on mean pulmonary artery pressure and V wave amplitude at rest and on mean right atrial and mean pulmonary artery wedge pressures at rest and during isometric exercise. In comparison with hydralazine alone, combination therapy enhanced the reduction in right atrial pressure (4 +/- 1 versus 0 +/- 2 mm Hg, p < 0.05), mean pulmonary arterial pressure (11 +/- 5 versus 1 +/- 3 mm Hg, p < 0.05), and the V wave amplitude (15 +/- 6 versus -5 +/- 3 mm Hg, p < 0.05) at rest and resulted in a larger reduction in exercise values of mean pulmonary artery pressure (-11 +/- 7 versus -3 +/- 5 mm Hg, p < 0.05) and mean pulmonary arterial wedge pressure (-11 +/- 5 versus -5 +/- 3 mm Hg, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Calcium channel blockers in heart failure.

The rationale for the use of calcium channel blockers in patients with chronic heart failure lies in their vasodilator action, antiischemic effect, ability to lessen left ventricular diastolic dysfunction and data showing their effect in preventing progression of myocardial dysfunction in animals with cardiomyopathy. Despite initial studies reporting improvement of the hemodynamic profile with nifedipine, further evaluation showed variable results, with hemodynamic worsening seen in up to 29% of patients. Longer-term controlled studies evaluating symptoms and clinical status demonstrated worsening chronic heart failure in approximately 25% of patients within 8 weeks of nifedipine therapy. Although diltiazem has a lesser myocardial depressant effect and its short-term use was associated with less frequent hemodynamic and clinical worsening, long-term exposure to the drug in a large group of patients with chronic heart failure due to left ventricular systolic dysfunction after myocardial infarction resulted in an increased incidence of cardiac events, with worsening heart failure and death. The use of verapamil in a similar patient cohort showed the loss of its demonstrated protective effect in patients with clinical evidence of heart failure. In an attempt to improve the safety of calcium channel blockers, the following approaches were suggested: 1) use of second-generation drugs with less myocardial depressant effect; 2) concomitant use of angiotensin-converting enzyme inhibitors to prevent reported neurohormonal activation; and 3) development of drugs with favorable neurohormonal effects. These approaches led to mixed results.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium Channel Blockers↗
PubMed1993

Plasma cyclic guanosine monophosphate in chronic heart failure: hemodynamic and neurohormonal correlations and response to nitrate therapy.

This study evaluated the relation between plasma cyclic guanosine monophosphate (cGMP) and hemodynamic and neurohormonal parameters in patients with chronic congestive heart failure and assessed the effect of organic nitrate on plasma cGMP levels. Plasma cGMP was fourfold higher in 18 patients with congestive heart failure compared with 15 control subjects (16.7 +/- 9.7 versus 4.0 +/- 1.0 pmol/ml; p < 0.0001) but did not correlate with plasma levels of catecholamines, renin, atrial natriuretic peptide, or with baseline hemodynamic values. The administration of a hemodynamically effective dose of oral isosorbide dinitrate (40 mg) resulted in a transient reduction in plasma cGMP from 16.7 +/- 9.7 pmol/ml at baseline to 13.0 +/- 6.6 pmol/ml at 1 hour (p < 0.05). This change was associated with small and statistically insignificant changes in neurohormonal values and had no relation to any of the hemodynamic changes. We concluded that (1) elevated plasma cGMP in congestive heart failure does not correlate with other neurohormonal or hemodynamic parameters and may be an independent parameter of heart failure, (2) in contrast to previously documented nitrate-mediated increases in intracellular cGMP, nitrate therapy results in a reduction in plasma cGMP, and (3) changes in plasma cGMP cannot serve as a surrogate measurement of changes in intracellular cGMP.

Administration, Oral↗
PubMed1992

Possible mechanisms of nitrate tolerance.

Prolonged exposure to organic nitrates has been shown to lead to the rapid development of tolerance to the peripheral and coronary vasodilatory effects of these drugs. As a result of this phenomenon, the hemodynamic and anti-ischemic effects of nitrates may be rapidly attenuated in patients with ischemic heart disease, congestive heart failure, or both. This nitrate tolerance appears to be both dose- and time-dependent. Likely mechanisms proposed for its development are multifactorial and include depletion of sulfhydryl groups, a nitrate-mediated increase in blood volume, and neurohormonal stimulation with activation of vasoconstrictive mechanisms.

Coronary Circulation↗
PubMed1992

Persistent hemodynamic improvement with short-term nitrate therapy in patients with chronic congestive heart failure already treated with captopril.

To evaluate the therapeutic potential of organic nitrates in patients with chronic congestive heart (CHF) failure already treated with angiotensin-converting enzyme (ACE) inhibitors, the temporal hemodynamic effects of oral isosorbide dinitrate, 40 to 120 mg administered every 6 hours to 11 nitrate responders who had been treated with captopril 89 +/- 32 mg/day, were studied. The administration of isosorbide dinitrate resulted in a significant decline in mean right atrial pressure, from 13 +/- 6 mm Hg at baseline (mean value of measurements performed every 2 hours for 24 hours with captopril therapy) to 9 +/- 4 mm Hg at 1 hour with persistent effect for most of the study period. Mean pulmonary artery pressure decreased from 38 +/- 7 mm Hg at baseline to 29 +/- 9 mm Hg at 1 hour, with effect persisting for 24 hours. Mean pulmonary artery wedge pressure also decreased from 24 +/- 6 to 15 +/- 7 mm Hg at 1 hour and remained significantly reduced for 20 hours. Systemic blood pressure demonstrated a transient decrease lasting 2 hours after initiation of therapy which was asymptomatic in all patients. The results of this study demonstrate a preserved vasodilatory effect of organic nitrates in patients already treated with ACE inhibitors. Nitrates mediated improvement in right and left ventricular filling pressures, and reduction of pulmonary hypertension demonstrates a rationale for the use of these therapeutic methods in combination and suggest the need for long-term evaluation of the effect of nitrate therapy in patients with chronic CHF already treated with ACE inhibitors.

Adult↗
PubMed1992

Nitrate resistance and tolerance: potential limitations in the treatment of congestive heart failure.

Organic nitrates are commonly used in the treatment of chronic congestive heart failure (CHF). These drugs have been shown to improve exercise capacity and reduce symptoms and in combination with hydralazine to prolong life in patients with mild-to-moderate symptoms of CHF. Recent investigations, however, have indicated that nitrate-mediated benefit to patients with CHF may be limited by resistance to their hemodynamic effects seen in many patients and by early development of tolerance. The incidence, potential mechanisms, and possible methods for prevention of nitrate resistance and tolerance in patients with chronic CHF are reviewed.

Drug Administration Schedule↗
PubMed1992

Effects of captopril on metabolic and hemodynamic alterations in global ischemia and reperfusion in the isolated working rat heart.

In the isolated working rat heart model, we studied metabolic and hemodynamic effects of 5- and 30-min global ischemia followed by reperfusion and assessed the potentially beneficial effect of captopril 80 micrograms/ml added throughout the experiment. Creatine kinase (CK) and catecholamines were measured in coronary effluent. De novo eicosanoids (prostaglandin E2) synthesis was assessed in endocardial explants. Hemodynamic alterations occurred after 30-min ischemia and were reflected most dramatically by a reduction in cardiac output (CO 72 +/- 10% of baseline values in captopril vs. 68 +/- 16% in controls) without significant differences as a result of treatment. Captopril shortened reperfusion ventricular fibrillation (VF) duration (6.9 +/- 1.2 vs. 13.6 +/- 8.7 min, p less than 0.05) but had no effect on VF incidence. No differences occurred in norepinephrine (NE) outflow, whereas total CK release was greater in controls. Five controls versus none of the treated hearts (p less than 0.05) released trace amounts of epinephrine during reperfusion. Increased de novo PGE2 synthesis was demonstrated after 5-min I (465 +/- 168 vs. 238 +/- 75 pg/100 mg tissue per hour, p less than 0.01). Captopril stimulated production of PGE2 in normoxic hearts (p less than 0.02), but the difference was no more apparent in ischemic hearts. We conclude that captopril produces some biochemical and electrophysiologic evidence of myocardial salvage, but these effects are not sufficient to induce hemodynamic improvement after global ischemia and reperfusion.

Animals↗
PubMed1991

Dissecting aortic aneurysm--failure of standard noninvasive and invasive diagnostic techniques.

The diagnosis of cardiac tamponade due to dissection of an ascending aortic aneurysm in a middle-aged woman was not confirmed by the usual noninvasive and invasive procedures. The decision for surgery was based on clinical grounds only, resulting in an unnecessary delay of surgical intervention. Although some of the current noninvasive techniques seem to be most useful in the investigation of these patients, the clinical findings remain the cornerstone of a correct diagnosis.

Aged↗
PubMed1991

Randomized study to evaluate the relation between oral isosorbide dinitrate dosing interval and the development of early tolerance to its effect on left ventricular filling pressure in patients with chronic heart failure.

BACKGROUND: Early development of nitrate tolerance has been shown in patients with chronic congestive heart failure (CHF) receiving continuous nitroglycerin therapy. The influence of dosing interval of oral isosorbide dinitrate (ISDN), the nitrate preparation most widely used for the treatment of CHF, has not been investigated. METHODS AND RESULTS: We performed a prospective, randomized study to evaluate the effect of various regimens of oral ISDN on the development of early tolerance to its effect on left ventricular filling pressure in patients with moderate to severe CHF. Forty-four responders (20% or greater reduction in mean pulmonary artery wedge pressure lasting 1 hour or longer) were divided into four groups of 11 patients each, and randomized to receive their effective ISDN dose (40-120 mg) Q 4 hours, Q 6 hours, Q 8 hours, or t.i.d. (drug given at 0, 6, 12, and 24 hours allowing 12 hours of ISDN washout interval between the third and fourth doses). All groups demonstrated a significant and comparable reduction in LV filling pressure following administration of the first ISDN dose. Early attenuation of hemodynamic response was demonstrated with frequent dosing (Q 4 hours and Q 6 hours) ISDN. Tolerance was with a Q 8-hour regimen as demonstrated by preserved hemodynamic response to each dose. The effect of each dose, however, was short-term, with return of pulmonary artery wedge pressure to baseline level at 2 to 4 hours, resulting in an intermittent effect totaling no longer than 12 hours of the 30-hour study period. The use of a t.i.d. regimen resulted in marked attenuation of response after the third dose with complete restoration of nitrate effect following a 12-hour washout period between the third and fourth doses. ISDN plasma concentration was measured in five patients in each of the Q 4- and Q 8-hour groups. In the Q 4-hour group, plasma levels were significantly higher after administration of the last dose than after the first dose (area under the curve, 242 +/- 216 versus 123 +/- 130 ng/ml, p less than 0.05), and trough levels before administration of the second and the fifth dose (15 +/- 17 and 27 +/- 27 ng/ml, respectively) were both markedly higher than the baseline value of 2 +/- 4 ng/ml. CONCLUSIONS: Our data demonstrate the development of tolerance and early attenuation of effect on left ventricular filling pressure with frequent oral dosing (Q 4 and Q 6 hours) with ISDN in patients with chronic CHF, which may be related to persistently elevated trough blood levels of ISDN. The development of tolerance can be reversed after a washout period of 12 hours and can be prevented with a Q 8-hour administration. These regimens, however, are limited by an inconsistent effect. Although long-term implications of these findings need further evaluation, the present study demonstrates the difficulty of maintaining a persistent ISDN-mediated reduction in left ventricular filling pressure in patients with chronic, moderate to severe CHF. These results suggest the need to use intermittent ISDN therapy allowing a daily nitrate washout interval and the rationale for combined vasodilator therapy in patients with CHF.

Drug Administration Schedule↗
PubMed1988

Haemodynamic effects of intravenous isosorbide-5-mononitrate in acute and chronic left heart failure of ischaemic aetiology.

Isosorbide-5-mononitrate was administered in a continuous intravenous infusion, according to the haemodynamic response, to 19 patients with left heart failure of ischaemic aetiology; 12 with acute heart failure complicating an acute myocardial infarction and 7 with chronic ischaemic failure. In both groups, the following statistically significant haemodynamic changes were observed: a decrease in PCWP from 25.4 +/- 4.6 to 17.2 +/- 4.6 mmHg; an increase in SWI from 19.1 +/- 10 to 23.6 +/- 13.1 gm m-2; a slight increase in cardiac index with no change in arterial pressure and only minimal decrease in vascular resistance. There were two major differences in the haemodynamic response between the patients with acute heart failure and those with chronic disease: (a) the duration of the effect of isosorbide-5-mononitrate on the PCWP was longer in the first group (mean, 8 hours, compared to 1.5 hours in the chronic group), and (b) the effect on afterload was more pronounced in the group with chronic ischaemic failure than in the first group. Thus, isosorbide-5-mononitrate administered by intravenous infusion under careful monitoring appears to have a beneficial role in the treatment of acute as well as chronic ischaemic heart failure.

Aged↗
PubMed1984

Prosthetic valve endocarditis in pregnancy.

A case of prosthetic valve endocarditis is described, caused by Streptococcus viridans in the third trimester of pregnancy. During her illness, the patient gave birth to a normal baby in an uncomplicated vaginal delivery. She had recurrent post-partum vaginal bleeding. Aspects relevant to the management of the case are discussed.

Adult↗