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Biomedical subjects

A Merdler

Publications and source records attributed to A Merdler.

33 records · Page 2Linked to original sources
PubMed1990

Nitrate tolerance in heart failure: differential venous, pulmonary and systemic arterial effects.

The hemodynamic profile of tolerance to intravenous nitroglycerin was studied in 9 patients with New York Heart Association Class III to IV congestive heart failure. After rapid dosage build-up to the maximal tolerated dose (decrease in pulmonary wedge pressure to 10 mm Hg or systolic blood pressure to 90 mm Hg), nitroglycerin (525 +/- 548 micrograms/min) was administered at a constant continuous intravenous infusion for a total of 24 hours. The extent of nitrate tolerance at 24 hours was calculated as the percentage loss of the benefit achieved at time of peak effect of nitroglycerin. Tolerance had a different time course and magnitude in the venous, arterial and pulmonary circulations. At 24 hours, right atrial pressure and pulmonary vascular resistance returned to control values in most patients, while 40 to 50% of the effect on systemic vascular resistance, cardiac index and pulmonary wedge pressure was maintained. These findings emphasize the importance of precise definitions in studies relating to nitrate tolerance.

Adult↗
PubMed1990

Predicting late restenosis after coronary angioplasty by very early (12 to 24 h) thallium-201 scintigraphy: implications with regard to mechanisms of late coronary restenosis.

To examine whether late coronary restenosis may be predicted by abnormalities of myocardial perfusion in the early hours after successful percutaneous transluminal coronary angioplasty and to study in greater detail the mechanisms involved in the development of late coronary restenosis after angioplasty, a prospective study was undertaken in 90 consecutive patients. Thallium-201 scintigrams were recorded at rest and during the stress of atrial pacing, 12 to 24 h after angioplasty, and the results were related to the findings at angiography in 70 patients undergoing late cardiac catheterization. A reversible thallium-201 perfusion defect was found in 39 (38%) of 104 myocardial regions supplied by the dilated coronary vessel and identified a subset of patients at high risk of late (6 to 12 months) angiographic restenosis (sensitivity 77%, specificity 67%). In contrast, late coronary restenosis developed in only 7 (11%) of 65 vessels and in 5 (14%) of 37 patients with a nonischemic thallium-201 scintigram on day 1 (p less than 0.005). Multivariate logistic regression analysis of 14 possible preangioplasty and periangioplasty clinical and angiographic variables selected reversible perfusion defect on the thallium-201 scintigram on day 1 (p = 0.016) and immediate postangioplasty residual coronary narrowing (p = 0.004) as significant independent predictors of late restenosis, with younger patient age as an additional less powerful predictor (p less than 0.05). The findings have important implications regarding the pathogenesis of late coronary restenosis in patients undergoing successful angioplasty and they imply that in the majority of these patients pathophysiologic events in the early minutes and hours after angioplasty may determine the development of late restenosis.

Adult↗
PubMed1989

Identifying patients at high risk for restenosis after percutaneous transluminal coronary angioplasty for unstable angina pectoris.

To study the determinants of late restenosis after percutaneous transluminal coronary angioplasty (PTCA) performed in patients with unstable angina pectoris, a prospective study was undertaken in 90 patients. Primary PTCA success was achieved in 84 (93%) patients, dilating 116 of 118 coronary narrowings (1.4/patient), while major complications during PTCA occurred in only 1 patient (1 death). Eighty-two patients (114 dilated arteries) were followed for 25 +/- 11 months: 68 (83%) were in New York Heart Association functional class I or II, 11 (13%) in class III, and there were 3 deaths. Late restenosis was found in 16 (25%) of 65 lesions (29% of 49 patients) studied by angiography 9 +/- 7 months after PTCA. Restenosis was more frequent in left anterior descending coronary artery lesions (p = 0.07) and in those which at the time of PTCA had multiple irregularities (67 vs 14%, odds ratio 12.5, p = 0.002), decreased coronary perfusion (Thrombolysis in Myocardial Infarction grade less than 3) (50 vs 15%, odds ratio 5.7, p = 0.02) or intraluminal thrombus (67 vs 19%, odds ratio 8.7, difference not significant). Multiple irregularities (p = 0.003) and decreased flow (p = 0.02) remained independent predictors of restenosis (goodness of fit 0.88) after adjustment for 12 pre- and peri-PTCA clinical and angiographic variables by logistic regression analysis. These data underline the feasibility of early revascularization by PTCA in patients with unstable angina pectoris. Careful follow-up should be instituted in patients with multiple irregular lesions, decreased coronary perfusion or intraluminal thrombus at the time of PTCA. In such patients, late restenosis may be the rule rather than the exception.

Adult↗
PubMed1989

[Percutaneous transluminal coronary angioplasty after coronary artery bypass].

Anginal syndrome may recur early of several years after coronary artery bypass surgery (CABS), and may be due to narrowing of a bypass graft, progression of pre-existing coronary artery lesions, or the appearance of new lesions. Repeat CABS is associated with considerable morbidity and mortality. We therefore performed percutaneous transluminal angioplasty (PTCA) in saphenous or internal mammary bypass grafts or native coronary arteries in 23 patients after CABS. We successfully dilated 35 of 37 lesions (95%) present in 33 of 35 vessels (94%) of 21 of 23 patients (91%). The mean vessel narrowing decreased from 86 +/- 22% to 13 +/- 19% (p less than 0.001) and in all 21 patients with angiographic evidence of success functional capacity improved. Single vein grafts were successfully dilated in 9 patients. None developed acute myocardial infarction or needed emergency surgery, but 1 had a cerebral embolism. PTCA is effective therapy for recurrent angina after CABS, and in many patients is preferable to another operation.

Angina Pectoris↗
PubMed1989

Effect of the second-generation calcium channel blocking drug nisoldipine on diastolic left ventricular dysfunction in heart failure.

The effect of intravenous nisoldipine (0.12 microgram/kg/min) on diastolic left ventricular (LV) dysfunction was studied from simultaneous hemodynamic and radionuclide measurements in 12 patients with New York Heart Association class II to IV cardiac failure. The initial LV filling fraction was low, the peak LV filling rate normalized for end-diastolic volume was decreased, and the pulmonary capillary wedge pressure (PCWP) was high and associated with clinical shortness of breath. Nisoldipine produced an increase in LV filling fraction from 36 +/- 17% to 43 +/- 20% (p = 0.003). The increase in filling took place in both early and late diastole: peak early filling rate (PFR) increased in 11 of the 12 patients (p = 0.02) and late diastolic filling rate (atrial [A] wave in eight of them (NS). When the determinants of these changes, were examined further, it was found that in the control state PFR was inversely related to LV end-systolic volume (r = 0.77), whereas the A wave was related in exponential fashion to PCWP (preload) (r = 0.79). Nisoldipine did not change the slope of these relationships, and it did not alter the end-diastolic pressure-volume relationship, implying that inherent myocardial relaxation and distensibility were unaltered by the drug. In summary, nisoldipine improved measurements of diastolic LV dysfunction in patients with cardiac failure. This study illustrates the importance of considering ventricular loading conditions when analyzing and interpreting measurements of diastolic ventricular dysfunction. The measured changes in diastolic LV function during infusion of nisoldipine appear to be due to alterations in ventricular loading conditions rather than to a direct myocardial effect of the drug.

Aged↗
PubMed1988

Effect of the second-generation calcium channel blocker nisoldipine on left ventricular contractility in cardiac failure.

We studied the acute effects of nisoldipine, a new second-generation calcium channel-blocking drug, on cardiac hemodynamics and left ventricular (LV) contractility in 10 patients with grade 2 to 4 cardiac failure. Pressures were measured from an arterial line and a flow-guided catheter in the pulmonary artery, cardiac output by thermodilution, and LV ejection fraction simultaneously by radionuclide ventriculography. Ventricular loading conditions were altered by sublingual nitroglycerin to facilitate construction of LV end-systolic pressure (radial stress)-volume and stress-shortening curves. Nisoldipine, given by continuous intravenous infusion (0.12 micrograms/kg/min), reduced mean arterial pressure (p = 0.001), systemic vascular resistance (p less than 0.05), and the double product, a measurement of myocardial oxygen demand (p less than 0.01). Cardiac index, stroke index, and LV ejection fraction increased in 8 of the 10 patients. LV contractility was initially greatly reduced and was unchanged or slightly decreased during the administration of nisoldipine. Emax, the slope of the end-systolic pressure-volume curve, was unaltered in half of the patients and decreased in the others (NS), whereas the end-systolic stress-shortening curve did not change. In summary, nisoldipine has a potentially useful acute hemodynamic profile in patients with cardiac failure; it increases forward blood flow in most patients, decreases the determinants of myocardial oxygen demand, and produces little measurable changes in the inotropic state of the left ventricle.

Aged↗
PubMed1988

Synergistic effect of captopril and dobutamine on left ventricular pressure-volume and pressure-shortening relations in severe cardiac failure.

The acute effects of captopril and dobutamine, alone and in combination, on left ventricular contractility were assessed from left ventricular end-systolic pressure-volume and pressure-shortening relations in 6 patients with severe end-stage cardiac failure. Dobutamine was given by constant intravenous infusion on two occasions 48 hours apart, on one of these occasions the patient also received oral captopril in a dose of 37 +/- 12 mg 6-hourly. Pressures and cardiac index were measured, and left ventricular volumes and ejection fraction computed from simultaneously recorded radionuclide ventriculography. Dobutamine alone did not cause a statistically significant increase in stroke index, stroke work index, cardiac index and ejection fraction, although pulmonary capillary wedge pressure and right atrial pressure fell (P less than 0.05). There was no change in systemic or pulmonary vascular resistance nor in arterial blood pressure. Following administration of captopril, diastolic arterial pressure decreased (P less than 0.05), and the dobutamine challenge produced a greater and significant rise in stroke and stroke work index (P less than 0.05) and cardiac index (P less than 0.01). The left ventricular contractile state was unaltered by captopril but appeared to increase with dobutamine and more so during combined therapy with captopril and dobutamine, indicating a synergistic effect of the two drugs when given in combination.

Aged↗
PubMed1988

Short- and long-term results of angioplasty for multiple coronary stenoses.

Sixty-eight patients underwent percutaneous transluminal coronary angioplasty (PTCA) for multiple coronary stenoses. Lesions involved one coronary vessel in 24 patients, two in 34, and three or more vessels in 10 patients. The primary patient success rate was 96%, and we successfully dilated 162 (91%) of 179 significant (i.e., greater than 70% obstructive) coronary lesions, mean 2.4 lesions/patient. Complete coronary revascularization was achieved in 24 patients (Group 1), while major narrowings were not dilated either by intention or due to failure of dilation in 42 others (Group 2). The clinical state of the patients improved markedly after successful PTCA, and 44 (72%) of 61 were in the New York Heart Association Functional Class I or II 3 to 24 months later. In keeping with the clinical results, there was a significant improvement in treadmill exercise performance, in both groups. Patients with complete revascularization, however, tended to exercise longer (NS) to a greater heart rate (P less than 0.004) with less or no ischemic ST depression on ECG (P less than 0.04). Complications were few and limited to patients undergoing PTCA for unstable angina pectoris or following acute myocardial infarction. One patient (1%) died, two (3%) had Q-wave infarction and one patient sustained a cerebral embolus during catheterization. Restenosis was observed in 6 (29%) of 21 consecutive patients recatheterized 6 to 12 months (or sooner for symptoms) after successful PTCA. Four patients underwent a repeat PTCA, one was referred for coronary artery bypass grafting (CABG), and in one restenosis was minor and symptoms were mild. PTCA should be considered in patients with multiple coronary stenoses in whom all or most of the significant lesions can be dilated. Partial revascularization by PTCA is clinically useful and may be preferable to CABG in patients in whom the surgical risk is increased.

Adult↗
PubMed1987

Chronotropic effect of hydralazine and its mechanism of symptomatic sinus bradycardia.

The positive chronotropic effect of hydralazine was studied in 9 patients with symptomatic sinus bradycardia. Hydralazine was given in an intravenous dose of 0.15 mg/kg and heart rate, blood pressure, sinoatrial conduction time (Narula method) and corrected sinus node recovery time were measured. The effect of hydralazine was also studied after total autonomic nervous system blockade using 0.04 mg/kg of atropine and 0.2 mg/kg of propranolol intravenously. In the control state hydralazine produced an increase of 28 +/- 15% (mean +/- standard deviation) in heart rate, and this was essentially due to a decrease in sinoatrial conduction time (by 32 +/- 32%, p less than 0.05). Corrected sinus node recovery time also tended to shorten (decrease of 21 +/- 34%, difference not significant). After total autonomic blockade intrinsic heart rate did not change or increased very little (9 +/- 14%) after administration of hydralazine and there was no consistent change in sinoatrial conduction and corrected sinus node recovery times. The small residual effect of hydralazine on heart rate was related to incomplete autonomic blockade, since the effect of postural change (standing) on heart rate was also not totally abolished. The study showed that the positive chronotropic effect of hydralazine was mainly due to a change in sinoatrial conduction with a smaller change in corrected sinus node recovery time, and the major chronotropic effect of the drug was mediated by the autonomic nervous system.

Aged↗
PubMed1987

Effect of captopril on left ventricular end-systolic pressure-volume and stress-shortening relations in severe cardiac failure.

The effects of captopril on cardiovascular dynamics and left ventricular (LV) contractility were studied in 11 patients with severe congestive heart failure and very poor global LV function. Pressures were measured using a flow-guided catheter, cardiac output by thermodilution, and LV contraction and ejection fraction by simultaneous radionuclide angiography. Ventricular loading conditions were altered by sublingual isosorbide dinitrate to facilitate construction of LV pressure-volume and stress-shortening curves. Captopril decreased mean arterial pressure (p less than 0.02) and systemic vascular resistance, while stroke and cardiac index increased in most patients. Left ventricular ejection fraction increased from 18 +/- 5 to 22 +/- 7% (p less than 0.05), but contractility, assessed from end-systolic pressure-volume and end-systolic pressure-shortening relations, was unchanged or decreased slightly. Heart rate and double product also tended to decrease. In contrast, arteriovenous oxygen difference widened and calculated total oxygen consumption increased during captopril therapy (p less than 0.05). The study showed that captopril improved forward blood flow, total oxygen extraction, and LV ejection fraction following the decrease impedance to LV emptying but not at the expense of an increase in ventricular contractility. This makes captopril an attractive drug for patients with end-stage cardiac failure and a severely damaged myocardium.

Aged↗
PubMed1987

Coronary artery to bronchial artery anastomosis in Takayasu's arteritis.

A 27-year-old woman presented with ischemia of the left arm and dizziness together with acute lateral wall myocardial ischemia. Physical examination showed narrowing of the arteries to the head and neck and upper limbs suggesting Takayasu's arteritis. Angiography demonstrated pulmonary and systemic involvement. There was complete occlusion of the right upper lobe pulmonary artery and a large collateral artery from the circumflex coronary artery which anastomosed with the right bronchial artery. This anastomotic channel has not to our knowledge been described Takayasu's arteritis.

Adult↗
PubMed1983

Beta blockade in asymptomatic diabetics with abnormal rest electrocardiograms.

Diabetic patients without evidence of vascular disease often reveal non-specific ST-T changes and prolonged QTc intervals in their ECGs. In an attempt to elucidate the role of autonomic dysfunction in the etiology of these changes, we compared the ECGs and beat to beat variations in 22 patients with changes in repolarization before and one hour after beta blockade. None had clinical evidence of ischaemic heart disease or peripheral vascular disease. In 19 patients (86%) the ST-T changes persisted after beta blockade. Heart rate was 75.6 +/- 15.3/min before and 64.3 +/- 9.6/min after beta blockade, while the QTc interval was 0.43 +/- 0.02 sec before and 0.41 +/- 0.02 sec after propranolol. Beat to beat variation during deep breathing is diminished in diabetic patients. Beta blockade reversed this phenomena. We conclude that while beat to beat variations and prolongation of QTc are likely to be consequent to autonomic neuropathy, the ST-T changes do not appear to be due to increased sympathetic tone and their etiology is yet to be determined.

Adolescent↗
PubMedDate not supplied

Determinants of improvement in exercise capacity in patients undergoing cardiac rehabilitation.

In order to identify patients who benefit most from a cardiac rehabilitation program, we studied retrospectively all patients who completed a 3-month comprehensive cardiac rehabilitation program during a 2-year period. Questionnaires regarding physical exercise habits were sent to 122 patients and returned by 117 (96%) of them (53 post-acute myocardial infarction, 50 post-coronary artery bypass surgery, 14 post-infarction and surgery, 2 post-angioplasty). Exercise capacity (subset of 66 patients) improved by 19% after rehabilitation (7.8 +/- 3.1 to 9.3 +/- 2.7 METs, p < 0.0001). Univariate and multivariate analysis identified initial exercise capacity as the only independent variable predicting improvement in exercise performance (inverse relationship) (r2 = 0.24, p < 0.0001). The improvement was not related to age, sex, left ventricular function or time from cardiac event to rehabilitation. Patients recovering from both infarction and coronary artery bypass surgery showed a greater improvement (delta exercise capacity 2.8 +/- 1.4 METs) than patients after myocardial infarction alone (delta exercise capacity 0.8 +/- 2 METs, p < 0.02). Improvement was sustained for up to 2 years after completion of the program.

Adult↗
PubMedDate not supplied

Exercise testing in patients with chest pain and normal coronary arteries: improving test specificity by use of a simple logistic model.

Despite an exercise electrocardiogram (ECG) positive for ischemia by established criteria, many patients referred for coronary angiography to evaluate chest pain are found to have angiographically normal coronary arteries (NCA). Exercise ECG were analyzed from 27 patients with chest pain and angiographically NCA and 28 patients with chest pain and coronary artery disease (CAD) using univariate and multivariate logistic regression analysis. We derived the following logistic model for the logit probability of CAD: 3 + SEX x 4 - METs x 0.7 + STDV5 x 0.8, where SEX = 0 for female and SEX = 1 for male, METs = maximal estimated work load (metabolic equivalents) and STDV5 = horizontal or downsloping ST depression (mm) in V5. A logit probability > or = 0 identified CAD with a sensitivity of 79% and a specificity of 89%. The model correctly identified 28/36 (78%) patients with CAD, and 7/10 (70%) patients with NCA (correct diagnosis 76%; p < 0.02) in a separate random group of 46 unselected patients with positive exercise tests undergoing diagnostic coronary angiography.

Adult↗