Search PubMed⌕ Search

Biomedical subjects

J Strom

Publications and source records attributed to J Strom.

At least 19 recordsLinked to original sources
PubMed1997

Exercise training in patients with severe congestive heart failure: enhancing peak aerobic capacity while minimizing the increase in ventricular wall stress.

OBJECTIVES: The aims of the study were to 1) assess the effects of 12 weeks of exercise training at low work loads (i.e., corresponding to < or = 50% of peak oxygen consumption [Vo2]) on peak Vo2 and hyperemic calf blood flow in patients with severe congestive heart failure; and 2) evaluate left ventricular diastolic pressure and wall stress during exercise performed at work loads corresponding to < or = 50% and 70% to 80% of peak Vo2. BACKGROUND: Whether the benefits of exercise training can be achieved at work loads that result in lower left ventricular diastolic wall stress than those associated with conventional work loads is unknown in patients with severe congestive heart failure. METHODS: Sixteen patients with severe congestive heart failure trained at low work loads for 1 h/day, four times a week, for 12 weeks. Peak Vo2 and calf and forearm reactive hyperemia were measured before and during training. Nine of the 16 patients underwent right heart catheterization and echocardiography during bicycle exercise at low and conventional work loads (i.e., 50% and 70% to 80% of peak Vo2, respectively). RESULTS: The increase in left ventricular diastolic wall stress was substantially lower during exercise at low work loads than during exercise at conventional work loads, (i.e., [mean +/- SEM] 23.3 +/- 7.4 vs. 69.6 +/- 8.1 dynes/cm2 (p < 0.001). After 6 and 12 weeks of training, peak Vo2 increased from 11.5 +/- 0.4 to 14.0 +/- 0.5 and 15.0 +/- 0.5 ml/kg per min, respectively (p < 0.0001 vs. baseline for both). Peak reactive hyperemia significantly increased in the calf but not in the forearm. The increases in peak Vo2 and calf peak reactive hyperemia correlated closely (r = 0.61, p < 0.02). CONCLUSIONS: In patients with severe congestive heart failure, peak Vo2 is enhanced by exercise training at work loads that result in smaller increases in left ventricular diastolic wall stress than those observed at conventional work loads.

Aged↗
PubMed1989

Sustained high-dose nitroglycerin transcutaneous patch therapy in angina pectoris: evidence for attenuation of effect over time.

The safety and efficacy of using continuous high-dose transcutaneous nitroglycerin in doses up to 100 mg/24 hours in chronic stable angina was assessed in 20 patients using serial treadmill testing. Patients had first to show a response to sublingual nitroglycerin with a 20% improvement in exercise time. All patients were then titrated with 20 mg (40 cm2), 60 mg (120 cm2), 80 mg (160 cm2) or 100 mg (200 cm2) patches, until intolerable headache in association with a 10 mmHg reduction in blood pressure and a ten-beat increment in heart rate. Drug was then discontinued for 2 days and patients underwent three repeat stress tests to reestablish a consistent drug-free baseline. Patients were then randomized in double-blind fashion to receive either active patch (N = 11) in previous titration dose or placebo patch (N = 9), with treadmill tests performed at 0 (1 hour after previous patch removal), 4, and 24 hours after patch application at baseline and at weeks 1 and 2. Venous blood was obtained for measurement of plasma nitroglycerin levels. After the first 24 hours of active patch therapy, there was a significant reduction in systolic blood pressure (P = .05), a significant increase in heart rate (P = .01), and a minor increase in exercise tolerance (P = .06) compared to placebo. At weeks 1 and 2, there was an attenuation of drug effect in all of these parameters. Plasma nitroglycerin levels demonstrated consistently high plasma levels over each 24-hour dosing interval, on day 1, week 1, and week 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗
PubMed1989

Effect of isometric exercise on cardiac performance and mitral regurgitation in patients with severe congestive heart failure.

Left ventricular performance was studied during isometric exercise in 17 patients with severe congestive heart failure, combining invasive hemodynamic and echo-Doppler techniques. Isometric exercise at 30% of maximum resulted in a decrease in stroke volume index (27.4 +/- 7.1 to 22.7 +/- 7.4 ml/m2), with a significant increase in heart rate from 81 +/- 10 to 92 +/- 14 beats/min and in systemic vascular resistance from 1827 +/- 527 to 2372 +/- 737 dyne.sec.cm-5. A significant rise in pulmonary capillary wedge pressure (18 +/- 9 to 31 +/- 10 mm Hg) was associated with a marked increase in mitral regurgitant volume (14 +/- 11 to 27 +/- 15 ml), calculated as the difference between total stroke volume obtained by two-dimensional echocardiography and forward stroke volume measured by pulsed Doppler at the aortic anulus. During isometric exercise, left ventricular end-diastolic and end-systolic volumes did not change markedly, but the total stroke volume tended to increase from 62 +/- 13 to 67 +/- 13 ml. The increase in mitral regurgitant volume induced by isometric exercise was correlated with the fall in forward stroke volume (r = 0.7, p less than 0.01). Thus a rise in systemic arterial pressure induced by isometric exercise is associated with a decrease in cardiac performance attributable to redistribution of total left ventricular output with an increase in mitral regurgitation and a simultaneous decrease in forward cardiac output.

Aged↗
PubMed1989

Dynamic mitral regurgitation. An important determinant of the hemodynamic response to load alterations and inotropic therapy in severe heart failure.

Cardiac performance and mitral regurgitation were measured by Doppler echocardiography and right heart catheterization in 12 patients with severe congestive heart failure who performed isometric exercise during control and intravenous administration of dobutamine and nitroglycerin. During control isometric exercise, mitral regurgitant volume increased from 18 +/- 13 to 31 +/- 17 ml (p less than 0.01), while forward stroke volume, by both thermodilution and Doppler echocardiography, substantially decreased. At rest, dobutamine decreased mitral regurgitant volume from 18 +/- 13 to 11 +/- 10 ml (p less than 0.05), while forward stroke volume increased from 46 +/- 13 to 55 +/- 15 ml (p less than 0.05). During isometric exercise, dobutamine tended to decrease mitral regurgitant volume (24 +/- 12 vs. 31 +/- 17 ml; NS) when compared with control exercise. At rest, nitroglycerin decreased mitral regurgitant volume from 18 +/- 13 to 11 +/- 11 ml (p less than 0.05), while forward stroke volume, by both thermodilution and Doppler echocardiography, substantially increased. Similarly, during isometric exercise, nitroglycerin decreased mitral regurgitant volume from 31 +/- 17 to 20 +/- 14 ml (p less than 0.05), while significantly increasing forward stroke volume. At control rest, the median mitral regurgitant fraction was 24% for the 12 patients. Neither dobutamine nor nitroglycerin changed significantly forward stroke and mitral regurgitant volumes at rest and during isometric exercise in the six patients with resting mitral regurgitant fraction below the median. In contrast, dobutamine and nitroglycerin significantly decreased mitral regurgitant volume and increased forward stroke volume both at rest and during isometric exercise in the six patients with mitral regurgitant fraction greater than the median.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Hemodynamic effects of flestolol, a titratable short-acting intravenous beta-adrenergic receptor blocker.

The hemodynamic effects of flestolol were evaluated in 30 patients undergoing routine cardiac catheterization. Hemodynamic measurements were obtained during baseline (prior to flestolol), at steady state during IV flestolol infusion (1, 5, and 10 micrograms/kg/min) and at 20 to 30 minutes after discontinuation (postinfusion). Flestolol-induced hemodynamic changes were similar to those induced by other beta blockers without intrinsic sympathomimetic activity. Significant dose-dependent reduction in heart rate, rate pressure product, and increase in peripheral vascular resistance were seen. Flestolol produced clinically insignificant decrease in myocardial contractility as shown by slight decrease in LVdp/dt, CI, and LVEF. Hemodynamic data from patients with paced heart rate, further confirms a direct mild cardiac depressant effect of flestolol, a finding common to other beta blockers. Consistent with the short elimination half-life of flestolol (t1/2 = 6.5 minutes), most of the hemodynamic changes rapidly returned to preinfusion level within 20 to 30 minutes following its discontinuation. Thus flestolol, with its unique pharmacokinetic profile and titrability, may be beneficial in the treatment of critically ill patients.

Adrenergic beta-Antagonists↗
PubMed1988

Noninvasive quantification of mitral regurgitation in dilated cardiomyopathy: correlation of two Doppler echocardiographic methods.

The presence and severity of functional mitral regurgitation were quantified by Doppler echocardiography in 17 patients with dilated cardiomyopathy and no evidence of primary valvular disease. Mitral regurgitant fraction was greater than 20% in 11 of the 17 patients, and exceeded 40% in four patients. Total stroke volume, calculated from the difference between end-diastolic and end-systolic volumes obtained by two-dimensional echocardiography, correlated well with mitral valve inflow determined by Doppler echocardiography (r = 0.90, p less than 0.001). Similarly, mitral regurgitant volume, calculated as the difference between echocardiographic total stroke volume and forward aortic volume obtained by Doppler echocardiography, correlated well with regurgitant volume calculated as the difference between mitral valve inflow and forward aortic flow, both determined by Doppler echocardiography (r = 0.90, p less than 0.001). Accordingly, functional mitral regurgitation can be conveniently demonstrated in patients with dilated cardiomyopathy by two different Doppler echocardiography methods, whose results are closely correlated. Mitral regurgitant fraction is greater than 20% in two thirds of the patients with a dilated cardiomyopathy.

Aged↗
PubMed1988

Diltiazem, nifedipine, and their combination in patients with stable angina pectoris: effects on angina, exercise tolerance, and the ambulatory electrocardiographic ST segment.

The efficacy and safety of oral nifedipine and diltiazem were compared in 20 patients with stable angina pectoris with use of a placebo run-in, randomized, double-blind titration to maximal effect crossover protocol. The effects of treatment withdrawal were also analyzed. All patients received placebo for 2 weeks and were then randomly assigned to receive either diltiazem or nifedipine. A 2 week drug titration phase in which patients received either diltiazem (180 to 360 mg/day) or nifedipine (30 to 120 mg/day) in three divided doses was followed by a 1 week maintenance phase. Patients then received placebo for 1 to 2 weeks, followed by crossover to the other treatment regimen and a second placebo washout period of 1 week. Patients (n = 13) who remained symptomatic on both diltiazem and nifedipine during the monotherapy periods entered a 3 week combination treatment phase, followed by a final 1 week placebo washout period. Frequency of angina, nitroglycerin consumption, exercise tolerance (Naughton protocol), and frequency of daily episodes of ST segment deviations on the electrocardiogram (1 mm of ST segment depression persisting for at least 1 min with and without chest pain) on an ambulatory electrocardiographic monitor were assessed during the baseline placebo, active monotherapy, placebo withdrawal, and combination treatment phases. Plasma drug levels were also measured. Compared with initial placebo values, the frequency of angina and the amount of nitroglycerin treatment were reduced by both diltiazem (p less than .001) and nifedipine (p less than .02). Diltiazem was more effective than nifedipine in reducing angina (p less than .02). Exercise duration increased with both drugs (p less than .0001). Diltiazem was significantly better than nifedipine in reducing the episodes of ST segment depression on the ambulatory monitor (p less than .01). Diltiazem reduced the resting heart rate (p less than .01); both drugs reduced the resting blood pressure and rate-pressure product. Overall, combination therapy was more effective in patients who did not maximally respond to diltiazem or nifedipine alone with respect to anginal and exercise variables and in reducing blood pressure at rest and during exercise. Plasma drug levels could not predict an individual patient's treatment response. Diltiazem may increase nifedipine drug levels when the drugs are combined. Fewer side effects were observed with diltiazem than nifedipine; the most side effects were seen with combination treatment. There were no apparent withdrawal effects observed with either treatment regimen.(ABSTRACT TRUNCATED AT 400 WORDS)

Angina Pectoris↗
PubMed1986

Twice-daily nicardipine in the treatment of essential hypertension.

The antihypertensive effect of twice-daily nicardipine, an investigational calcium-channel blocker, was evaluated in a placebo-controlled, single-blind trial in 18 adult patients with essential hypertension (supine diastolic blood pressure [BP] of greater than or equal to 95 and less than or equal to 120 mmHg). Following a 4-week run-in period in which patients received placebo for the final 2 weeks, nicardipine was administered for 12 weeks with a treatment goal of a supine diastolic BP of less than 90 mmHg at 12 hours postdosing or to a maximum dose of 60 mg twice daily. Supine and standing BPs and heart rates were determined at 1 hour and 12 hours postdosing. At all dose levels, supine and standing BPs were reduced at 1 hour after dosing, with partial loss of efficacy seen at 12 hours. Increases in heart rate seen at 1 hour were not significant at 12 hours. Eight patients withdrew from the study for minor, although troublesome, side effects, such as palpitations and headaches. These data suggest that nicardipine monotherapy given in a twice-daily dosing regimen has only a limited role to play in the chronic treatment of patients with essential hypertension.

Adult↗
PubMed1985

Comparison of diltiazem and nifedipine for both angina pectoris and systemic hypertension.

In a randomized, double-blind, placebo-controlled crossover trial, diltiazem and nifedipine were compared in 10 patients with stable angina pectoris and mild to moderate hypertension (supine diastolic blood pressure greater than or equal to 90 mm Hg). Patients received placebo for 2 weeks, then increasing doses of diltiazem (90 to 360 mg/day) or nifedipine (30 to 120 mg/day) in 3 daily divided doses over 2 weeks, followed by 1 week of therapy at the maximal dose, a 1-week placebo "washout," then crossover to the other drug. Heart rate and blood pressure at rest and during exercise, anginal frequency, nitroglycerin consumption and treadmill exercise tolerance were assessed. Compared with placebo, anginal frequency and nitroglycerin consumption were reduced with both diltiazem and nifedipine (p less than 0.01) and exercise tolerance was increased with both drugs (p less than 0.01). Standing blood pressure at rest was reduced by diltiazem and nifedipine (146.6 +/- 11.4/97.7 +/- 5.3 mm Hg at placebo, baseline reduced to 129.6 +/- 15.2/79.5 +/- 13.7 mm Hg with diltiazem, and to 122.2 +/- 9.9/82.0 +/- 7.1 with nifedipine, p less than 0.01 for both). Compared with placebo, diltiazem and nifedipine also reduced exercise diastolic blood pressure (p less than 0.01), but not systolic blood pressure. Diltiazem lowered the heart rate at rest from 88.5 +/- 14.4 beats/min at placebo baseline to 79.7 +/- 17.9 beats/min (p less than 0.01); the heart rate with diltiazem was 11 beats/min lower than that with nifedipine (p less than 0.05). Both diltiazem and nifedipine had similar effects on the heart rate-blood pressure product at rest and during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Lidoflazine and propranolol combination treatment in chronic stable angina.

The short-term (1 month) and long-term (6 months) safety of combination lidoflazine-propranolol therapy was investigated in an open trial of 15 patients with stable angina of effort. The possible advantages of adding lidoflazine (titrated to 360 mg daily) to patients having a therapeutic response to propranolol (80-400 mg daily) was also evaluated. Effects on non-invasive indexes of left ventricular function (echocardiography, systolic time intervals, radionuclide ventriculography) and exercise tolerance (treadmill exercise testing) were determined. There was no change in mean resting heart rate with the combination therapy, although one patient developed sinus bradycardia at a rate of 44 and had to have his propranolol dose reduced. Electrocardiographic analysis showed significant prolongation of the QTc intervals on lidoflazine-propranolol therapy compared to propranolol alone, with 3 patients having QTc interval prolongation to above .53 seconds, but there was no evidence of increased arrhythmogenesis with the combination therapy compared to propranolol alone. Left ventricular end-diastolic volume index tended to rise with combination therapy. However, lidoflazine-propranolol therapy did not produce any significant effects on resting ejection fraction determined by M-mode echocardiography or by radionuclide ventriculography. Radionuclide ventriculography determined peak exercise ejection fractions were also not significantly changed with combination therapy compared to propranolol alone. There were only small, insignificant improvements in exercise tolerance with the lidoflazine-propranolol combination treatment compared to propranolol alone. It is concluded that lidoflazine-propranolol combination therapy is generally safe but has the potential of causing serious adverse effects in certain patients, i.e. those with sick sinus disease, prolonged QTc intervals, and severe baseline left ventricular dysfunction, and that caution must be exercised in its use. Furthermore, it would appear that combination therapy provides only slight, if any, improvements in exercise tolerance in patients with chronic stable angina having a therapeutic response to oral propranolol.

Adult↗
PubMed1984

Fatigue-induced failure of the Ionescu-Shiley pericardial xenograft in the mitral position. In vivo and in vitro correlation and a proposed classification.

Four patients had signs of primary bioprosthetic dysfunction within the fourth postoperative year after mitral valve replacement with an Ionescu-Shiley pericardial xenograft; they represent approximately 9% of patients with Ionescu-Shiley pericardial xenograft mitral valves followed up for more than 3 years at our institution. Pathological investigation showed severe incompetence of all explanted valves due to cusp tears and lacerations. Histologic study of the pericardial tissue disclosed mild to moderate collagen degeneration, without infection or calcification. Neoendothelial formation on the Dacron cloth of the sewing ring was either absent or minimal. The high incidence of valvular incompetence prompted us to try to establish a correlation between the in vivo and in vitro modes of failure of the Ionescu-Shiley pericardial xenograft. For this purpose, 10 unimplanted Ionescu-Shiley pericardial xenograft valves were tested in a fatigue test system. Severe fatigue-induced lesions occurred in this group after an average of 29.09 +/- 17.26 X 10(6) cycles; initial failure could be recognized in six of them after an average of 16.94 +/- 20.12 X 10(6) cycles. Valves tested in the fatigue test system showed tears and lacerations similar to those noted in the Ionescu-Shiley pericardial xenografts obtained from the four patients (which were assumed to have functioned for more than 100 X 10(6) cycles in each case). Correlation between results of the fatigue testing and our clinical experience enabled us to recognize four types of tears which may occur in the Ionescu-Shiley pericardial xenograft. The results of this investigation showed the following: (1) Primary tissue failure of the Ionescu-Shiley pericardial xenograft may occur suddenly. (2) A classification of tears occurring in Ionescu-Shiley pericardial xenograft valves is useful since the clinical presentation of patients may differ according to type and location of the lesion. (3) In the manufacture of pericardial valves, particular care must be observed in selection of the tissue and in the frame design. (4) Improvement of the quality control is one of the clues to enhance durability of the Ionescu-Shiley pericardial xenograft.

Aged↗
PubMed1983

Improvement in exercise capacity despite cardiac deteriora tion: nonivasive assessment of long-term therapy with amrinone in severe heart failure.

Seven patients with severe congestive heart failure (CHF) were treated with oral amrinone for a mean duration of 39 weeks (range 16 to 72). During the first week of therapy, exercise capacity as assessed on a treadmill using the Naughton protocol, increased substantially from 7.6 +/- 4.2 to 12.1 +/- 4.4 minutes (p less than 0.01). At an early period of follow-up (8 to 12 weeks), a further significant increase in exercise capacity to 14.7 +/- 5.0 minutes (p less than 0.05) was demonstrated, while at a later follow-up exercise capacity had decreased to 11.4 +/- 6.8 minutes (p less than 0.05). This was still significantly greater than prior to amrinone therapy (p less than 0.01). Left ventricular ejection fraction was increased from 14 +/- 4 to 19 +/- 4% (p less than 0.05) during the first week of therapy, but was not significantly different from control at the early and late periods of follow-up. Left ventricular end-diastolic dimension index increased from control value of 43 +/- 5 to 47 +/- 7 mm/m2 (p less than 0.01) at the late period of follow-up. Thus long-term amrinone therapy resulted in a substantial improvement in exercise capacity despite a slow, but progressive decline in cardiac performance.

Adult↗
PubMed1983

Reproducible replacement of elongated or ruptured mitral valve chordae.

Anatomical rules that make it possible to accurately replace mitral anterior cusp chordae tendineae with tanned xenograft pericardium are defined. Anterior and posterior cusp chordae were replaced with xenograft and autologous pericardium in 11 patients who had ruptured or elongated chordae. The xenograft occasionally became calcified; however, because it did not become elongated or shortened, competence was maintained for up to 3 years. Insufficiency was corrected, and the correction maintained for up to 4 months. Degenerative disease proved easier to treat than rheumatic disease. Two-dimensional echocardiography was a valuable aid in both preoperative planning and postoperative evaluation.

Adult↗
PubMed1982

Comparative effects of abrupt withdrawal of propranolol and verapamil in angina pectoris.

The potential hazards of abrupt withdrawal of propranolol have been described in patients with angina pectoris; however, the effects of abrupt withdrawal from long-term therapy with verapamil have not previously been investigated. The comparative effects of withdrawal from long-term treatment with propranolol and verapamil were assessed in a placebo-controlled double-blind randomized crossover study of 20 patients received placebo for 2 weeks, then increasing doses of propranolol (60 to 320 mg/day) or verapamil (240 to 480 mg/day) for 3 weeks. Patients were then abruptly withdrawn from drug onto placebo for 1 week, followed by crossover to the other drug treatment and a second withdrawal period. All 20 patients were withdrawn from verapamil without evidence of a rebound increase in frequency of anginal attacks, blood pressure, heart rate, or rate-pressure product and without a rebound deterioration in exercise tolerance. In contrast, with propranolol withdrawal, 2 patients (with the highest baseline angina attack rate) had a severe exacerbation of their anginal syndrome and could not undergo formal exercise testing; the other 18 patients were withdrawn from propranolol without incident. Plasma catecholamines were increased during exercise compared with rest during all treatments; however, the levels of catecholamines during exercise were significantly higher with propranolol than with verapamil and placebo (p less than 0.05). Levels of exercise catecholamines returned to placebo baseline values after withdrawal of propranolol.

Angina Pectoris↗
PubMed1982

Physiologic mechanisms in aortic insufficiency. I. The effect of changing heart rate on flow dynamics. II. Determinants of Austin Flint murmur.

We studied the dynamic changes in mitral flow patterns and in mitral valve motion before and after producing acute, reversible aortic insufficiency (AI) in nine open-chest dogs. Phasic mitral flow, the mitral valve echocardiogram, and intracardiac phonocardiogram and other hemodynamic variables were measured. During moderate AI (mean regurgitant fraction 52 +/- 5%) (+/- SD), the antegrade filling volume decreased from 31 +/- 7 to 24 +/- 6 ml (p less than 0.01), but the peak protodiastolic mitral flow rate increased from 139 +/- 37 to 157 +/- 42 ml/sec (p less than 0.01), reflecting the shift of a larger fraction of total mitral filling volume to early diastole. In six dogs, atrial pacing was used to examine the hemodynamic effects of tachycardia. Increasing the heart rate from 90 to 120 beats/min increased cardiac output from 2.64 +/- 0.56 to 3.3 +/- 0.831/min (p less than 0.05) and decreased left atrial pressure from 24 +/- 8 to 17 +/- 7 mm Hg (p less than 0.05). Increasing heart rate to 150 beats/min compromised mitral filling, reduced cardiac output and increased left atrial pressure. Moderate tachycardia improves cardiac performance in AI by reducing regurgitant volume, without significantly reducing transmitral filling volume. The mitral valve echocardiogram showed only a small decrease in cusp opening amplitude during AI. A low-pitched left ventricular inflow tract murmur was recorded in protodiastole and corresponded in time to the rapidly increasing mitral flow. We conclude that the major determinant of the turbulence responsible for the creation of the austin flint murmur is the antegrade mitral flow stream and its mixing with the retrograde aortic flow.

Animals↗