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Biomedical subjects

J A Strom

Publications and source records attributed to J A Strom.

At least 37 records · Page 2Linked to original sources
PubMed1991

Acute hemodynamic effects of terazosin in hypertensive and normotensive patients.

Terazosin, a selective alpha 1-adrenergic antagonist, was administered intravenously to 10 patients undergoing cardiac catheterization to determine its short-term hemodynamic effects. Hemodynamic measurements were performed before and 30 minutes after three doses of the drug: 1, 1, and 3 mg. One milligram of terazosin reduced the blood pressure (systolic/diastolic, mean) from a mean of 152.0/86.3, 110.7 mm Hg by -24.3/-9.4, -15.3 mm Hg (p less than 0.05). In the five patients who received 5 mg of the drug, blood pressure declined in a dose-dependent manner by -21.8/-3.8, -11.6 mm Hg after 1 mg, and by -35.8/-14.8, -22.8 mm Hg (p less than 0.05) after all 5 mg of the drug. The changes in blood pressure paralleled the terazosin-induced decrease in systemic resistance. Similar changes were recorded for pulmonary artery and capillary wedge pressures and pulmonary vascular resistance. The greatest hemodynamic response was noted with the first drug dose; succeeding doses had a progressively diminished incremental effect. Cardiac output, heart rate, and maximum left ventricular dp/dt demonstrated little change, whereas left ventricular end-diastolic pressure decreased after all three doses, reaching significance after 2 mg (-3.4 +/- 0.9 mm Hg, p less than 0.05), and left ventricular ejection fraction tended to increase (+5.6% +/- 2.4%, p less than 0.05 after 1 mg) and showed a dose dependence analogous to that of systemic resistance. Although not generally reaching statistical significance, indexes of aortic stiffness and compliance displayed a favorable effect. These data are consistent with terazosin's specific alpha 1-antagonism. Left ventricular performance is improved by afterload reduction, since terazosin demonstrated no direct effect on cardiac contractility.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1991

Hypernatremia due to repeated doses of charcoal-sorbitol.

Hypernatremic dehydration due to unreplaced stool water losses often complicates the use of the osmotic cathartic lactulose in the treatment of hepatic encephalopathy. Sorbitol, another osmotic cathartic commonly used in the treatment of drug intoxications, has been reported in the pediatric literature to induce severe hypernatremia, but there is only a rare case report in an adult. We report a dramatic case of severe hypernatremia secondary to repetitive administration of activated charcoal-sorbitol suspension for the treatment of phenobarbital intoxication in an adult. Based on our experience with this case, several recommendations are provided regarding management of drug intoxications with charcoal-sorbitol suspension, including meticulous attention to fluid-electrolyte balance, type of replacement fluid, and dosing of the suspension.

Adult↗
PubMed1991

Atrial contribution to ventricular filling in mitral stenosis.

BACKGROUND: The importance of the contribution of atrial systole to ventricular filling in mitral stenosis is controversial. The cause of reduced cardiac output following the onset of atrial fibrillation may be due to an increased heart rate, a loss of booster pump function, or both. METHODS AND RESULTS: We studied the atrial contribution to filling under a variety of conditions by combining noninvasive studies of patients with computer modeling. Thirty patients in sinus rhythm with mild-to-severe stenosis were studied with two-dimensional and Doppler echocardiography for measurement of mitral flow velocity and mitral valve area (MVA). The mean +/- SD atrial contribution to left ventricular filling volume was 18 +/- 10% and varied inversely with mitral resistance. Patients with mild mitral stenosis (MVA, 1.8 +/- 0.7 cm2) and severe mitral stenosis (MVA, 0.9 +/- 0.2 cm2) had atrial contributions of 29 +/- 4% and 9 +/- 5%, respectively. The pathophysiological mechanisms responsible for these trends were further investigated by the computer model. In modeled severe mitral stenosis, increasing heart rate from 75 to 150 beats/min caused an increase of 5.2 mm Hg in mean left atrial pressure, whereas loss of atrial contraction at a heart rate of 150 beats/min caused only a 1.3 mm Hg increase. CONCLUSIONS: The atrial booster pump contributes less to ventricular filling in mitral stenosis than in the normal heart, and the loss of atrial pump function is less important than the effect of increasing heart rate as the cause of decompensation during atrial fibrillation.

Adult↗
PubMed1989

Mechanism of antihypertensive action of dilevalol compared with that of "cardioselective" beta-blocking agents.

The hemodynamic effects of dilevalol, a nonselective beta-adrenergic blocking agent with vasodilating properties, were evaluated in 34 hypertensive patients and compared with those of the "cardioselective" beta blockers atenolol and metoprolol in 21 patients. Hemodynamic measurements were obtained at baseline, after acute treatment (first dose) with dilevalol (400 mg) and atenolol (50 mg) or metoprolol (100 mg), and again after subchronic treatment with these agents. After both acute and subchronic treatment (mean daily dose 1,042 mg), dilevalol significantly reduced mean arterial pressure (MAP, p less than 0.0001), by significantly reducing systemic vascular resistance index (SVRI, p less than 0.001), and by not significantly altering cardiac index (CI). In contrast, atenolol and metoprolol significantly reduced MAP (p less than 0.002) by significantly reducing CI (p less than 0.0001), with a concomitant increase in SVRI (p less than 0.007). Heart rate (HR) was reduced significantly less (p less than 0.006) with dilevalol than with the cardioselective agents. Correlation of the decrease in MAP with other hemodynamic parameters revealed that the effects on MAP of acute treatment with the cardioselective drugs are related to a decrease in HR (r = 0.63, p = 0.002), whereas those of subchronic treatment are correlated to a decrease in CI (r = 0.59, p = 0.01). The decrease in MAP after acute and subchronic dilevalol treatment is correlated primarily with SVRI (r = 0.46 to 0.49, p less than 0.01) and only secondarily with HR (r = 0.34, p less than 0.05). Therefore, the main mechanism of antihypertensive action for dilevalol is vasodilation, in contrast to the cardioselective agents, which is beta blockade.

Adult↗
PubMed1989

Effects of dilevalol, metoprolol and atenolol on left ventricular mass and function in nonelderly and elderly hypertensive patients.

Using serial M-mode echocardiographic determinations of left ventricular (LV) mass and function, the effects of dilevalol, a selective beta 2 agonist with nonselective beta-antagonist properties, were compared with those of metoprolol in 2 centers in double-blind, randomized clinical trials using similar protocols in nonelderly hypertensive patients (aged less than 65 years) (study 1). In a separate bicenter study with a similar design, dilevalol was compared with atenolol in elderly hypertensive patients (aged greater than or equal to 65 years) (study 2). Patients in both studies received placebo for 2 to 4 weeks, and were then randomized to receive increasing doses of dilevalol (200, 400, 800, 1,600 mg) or metoprolol (100, 200, 300, 400 mg) in study 1, and dilevalol (100, 200, 400, 800 mg) or atenolol (50, 100 mg) in study 2, to achieve a supine diastolic blood pressure (BP) of less than 90 mm Hg. In both studies, LV function and mass (Penn convention) were determined by echocardiographic examinations performed before randomization and at the end of the active treatment phase. Dilevalol, metoprolol and atenolol significantly reduced BP compared with placebo. In the nonelderly patients, a modest reduction in LV mass was observed with dilevalol (p less than 0.03) but not with metoprolol. Indexes of LV function--as assessed by end-diastolic and end-systolic dimensions, LV ejection time and ejection fraction--were better preserved by dilevalol than by metoprolol. In the elderly, neither dilevalol nor atenolol affected LV mass; however, indexes of LV function were better preserved with dilevalol than with atenolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1989

Diagnosis of myocardial ischemia by the pressure-rate quotient and diastolic time interval during coronary artery bypass surgery.

Diagnosis of intraoperative myocardial ischemia by the rate-pressure product (RPP), pressure-rate quotient (PRQ), and diastolic time interval (DTI) was studied in 13 patients undergoing coronary artery bypass grafting (CABG) with fentanyl, vecuronium/pancuronium, and enflurane anesthesia. Criteria for ischemia were 1 mm of ST segment elevation or depression or T wave inversion on the ECG. RPP was calculated by multiplying the systolic arterial pressure (SAP) times the heart rate (HR); PRQ was determined by dividing the mean arterial pressure (MAP) by the HR; and DTI was defined as the interval from the closure of the aortic valve on M-mode transesophageal echocardiography to the onset of the QRS complex on the ECG. Six of 13 patients experienced episodes of ischemia (a total of 32 episodes out of 134 measurements). RPP of 12,000 was not found to correlate with myocardial ischemia (P greater than 0.05), whereas PRQ of less than 1.0 or DTI of less than 400 ms was associated with myocardial ischemia (P less than 0.005). In this preliminary study, it is concluded that both the PRQ and DTI are indicators of myocardial ischemia; it is also suggested that ischemia may be prevented by maintaining (1) DTI over 400 ms (HR less than 75 beats per minute), and (2) PRQ greater than 1.0 (MAP greater than HR).

Anesthesia, General↗
PubMed1989

Effects of calcium entry blockade on hypertension-induced left ventricular hypertrophy.

Left ventricular hypertrophy (LVH) is a structural adaptation of the heart and is a response to increased hemodynamic and metabolic demands, which are most commonly caused by systemic hypertension. LVH induced by hypertension is associated with reduced myocardial compliance, structural alterations, and changes in coronary perfusion. Calcium entry blockers have caused LVH regression both in experimental studies and in clinical trials. Although their efficacy as antihypertensive agents is primarily due to their vasodilating properties, the mechanisms by which calcium entry blockers accomplish LVH regression are complex and include various hemodynamic and neurohumoral factors. Calcium entry blockade has decreased LVH with no apparent deterioration of left ventricular function. Because LVH is a major risk factor for sudden cardiac death and other cardiac morbidities, it is possible that the regression of LVH can improve the prognosis in hypertensive patients.

Animals↗
PubMed1988

Serotonergic blockade compared with beta-adrenergic blockade in systemic hypertension: a double-blind comparison of ketanserin with propranolol.

The safety and efficacy of ketanserin, a competitive serotonin blocking agent, and propranolol were compared in 33 patients with mild to moderate hypertension (sitting diastolic blood pressure [DBP] 95-115 mm Hg) using a placebo run-in, randomized, double-blind parallel study design. All patients received placebo for 4 weeks, then were randomized to receive increasing doses of either ketanserin (20, 40 mg twice daily) or propranolol (40, 80 mg twice daily) to achieve a goal sitting DBP less than 90 mm Hg. Patients not achieving the goal blood pressure with either drug as monotherapy, received the other drug in combination. At the end of the active monotherapy phase (week 10 of the study), propranolol demonstrated a greater decrease in DBP from baseline, as compared to ketanserin (-7.9 +/- 10.9 mm Hg with propranolol, P less than 0.05; -1.0 +/- 7.2 mm Hg with ketanserin, P = NS). Four out of 16 patients achieved goal response on propranolol, compared to 3/17 for ketanserin. With combination treatment, 9/18 patients reached the goal response; the addition of propranolol to ketanserin in non-responders resulted in further reduction of sitting DBP of -10.3 +/- 6.3 compared to monotherapy (P less than 0.001), while the addition of ketanserin to non-responders produced no significant response in sitting DBP. Propranolol showed a consistent effect in slowing heart rate. Ketanserin displayed less frequent side effects than propranolol. Propranolol used twice daily appears to be more effective than twice daily ketanserin use in patients with mild to moderate hypertension.

Adrenergic beta-Antagonists↗
PubMed1988

Ultra-short-acting beta-adrenergic blockers.

The ultra-short-acting beta-adrenergic blockers are parenteral agents that can be rapidly titrated in clinical situations where immediate beta-adrenergic blockade is warranted. The effects of those drugs rapidly dissipate after termination of treatment, providing an important safety feature. Esmolol, the prototype drug of this class, is approved for treatment of supraventricular tachyarrhythmias but also has potential use in treatment of patients with perioperative hypertension and acute myocardial ischemia.

Adrenergic beta-Antagonists↗
PubMed1988

Acute cardiogenic pulmonary edema: clinical and noninvasive evaluation.

Left ventricular echocardiograms performed within ninety-six hours of admission were prospectively correlated with the clinical course in 87 consecutive patients admitted with acute pulmonary edema. Patients were stratified into four groups based on their two-dimensional echocardiogram: hyperdynamic, normal, mildly reduced, and severely reduced. Echocardiographic estimates of left ventricular function were compared with their ejection fraction measured by the gated radioisotope technique. The authors found that 48% of the patients were either normal or hyperdynamic (38% and 10% respectively). Patients in these two groups had a greater incidence of left ventricular hypertrophy (wall thickness greater than 13 mm) (66% vs 39%, p less than .05), hypertension on admission (BP greater than 160/100) (66% vs 41%, p = .05), and smaller end-diastolic dimension (p less than .05) than those with decreased left ventricular function. The authors conclude that echocardiography is a good screening test of left ventricular function in patients presenting with pulmonary edema. Patients with normal or increased left ventricular systolic function should be evaluated for correctable or treatable causes of acute pulmonary edema.

Acute Disease↗
PubMed1987

Long-term safety and efficacy comparison of immediate-release and sustained-release oral verapamil in systemic hypertension.

The long-term safety and efficacy of twice-daily sustained-release verapamil were assessed compared to thrice-daily immediate-release verapamil in 25 patients with mild to moderate systemic hypertension. Patients were monitored on immediate-release verapamil (480 mg/day) for 6 months and were then placed on twice-daily sustained-release verapamil for an additional 6 months. Immediate-release verapamil, with and without a diuretic, successfully controlled standing and sitting systolic and diastolic blood pressures (p less than 0.001) compared to pretreatment baseline values. The effects of verapamil on blood pressure were sustained for an additional 6 months when the sustained-release formulation was utilized. Both formulations were well tolerated, with no significant effects on heart rate. In conclusion, verapamil, in both the immediate- and sustained-release formulations, is equally effective in lowering blood pressure for up to 1 year.

Administration, Oral↗
PubMed1986

Dynamics of mitral regurgitation during nitroglycerin therapy: a Doppler echocardiographic study.

Seven patients with decompensated chronic heart failure and functional mitral regurgitation were studied before and during administration of nitroglycerin at a mean dose of 42 micrograms/min (range 20 to 90 micrograms/min). Forward aortic flow obtained by pulsed Doppler increased significantly from 35 +/- 8 to 45 +/- 9 ml/beat (p less than 0.001) and correlated well with the cardiac output measured by thermodilution technique (r = 0.8). Whereas regurgitant mitral volume calculated from the difference between echocardiographic total stroke volume and forward aortic flow decreased significantly from 19 +/- 9 to 3 +/- 3 ml/beat (p less than 0.001), peak velocity of mitral regurgitant flow increased from 4.1 +/- 0.9 to 4.4 +/- 1.0 m/sec (p less than 0.05). The decrease in effective mitral regurgitation area derived from a modified Gorlin formula average 80%. Accordingly, in patients with decompensated chronic heart failure and functional mitral regurgitation, nitroglycerin decreases mitral regurgitant area substantially, and thus almost abolishes mitral regurgitation despite an increase in systolic pressure gradient between left ventricle and atrium. Moreover, the increase in forward flow can be entirely accounted for by the reduction in mitral regurgitant flow.

Aged↗
PubMed1986

Right-sided valvular endocarditis: etiology, diagnosis, and an approach to therapy.

Right- and left-sided endocarditis are two distinct entities, both clinically and experimentally. As such, they require different clinical approaches. The accurate diagnosis of right-sided endocarditis rests largely on a high index of suspicion which is often raised in the case of an intravenous drug abuser with fever, especially when pulmonary infiltrates are detected. Two-dimensional echocardiography can be expected to confirm the diagnosis in approximately 80% of the cases. Measurement of the echocardiographically visualized vegetation provides both prognostic and therapeutic information. When the vegetation is less than 1.0 cm in diameter, antibiotic therapy can be reasonably expected to cure the infection. Despite a prolonged fever, we recommend continued medical management in these cases, as lack of response to medical management is almost exclusively seen in cases in which echocardiographically determined vegetation size is greater than or equal to 1.0 cm, perhaps because of the slower metabolic rate of bacterial colonies within these large vegetations. If, however, after 3 weeks of antibiotic therapy, fevers persist in a patient in whom two-dimensional echocardiography reveals a vegetation of greater than or equal to 1.0 cm, surgical intervention should be contemplated. Prior to such intervention, the physician must be careful to exclude other sources of fever, such as abscesses, phlebitis, and drug reactions, as indicated in Table III. Also, adequate antibiotic levels should be documented prior to surgical intervention. Because of the adverse effect on vegetation size upon the response to antibiotics, there may be a role for anticoagulation in order to potentiate the effects of the antibiotic therapy; however, this is purely speculative at present.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗
PubMed1986

Influence of vegetation size on clinical outcome of right-sided infective endocarditis.

Endocarditis involving right-sided valvular structures is largely a disease of intravenous drug abusers. The majority of these patients respond to antibiotic therapy with clearing of their bacteremia and preservation of their hemodynamic status. This study evaluated the prognostic value of echocardiographically determined vegetation size in 23 episodes of right-sided valvular endocarditis in 21 patients. Right-sided vegetations were visualized in 19 of 23 episodes (83 percent). Of these, a vegetation of 1.0 cm or greater was found in 11. No patient with an echocardiographically determined vegetation size of less than 1.0 cm required surgery, whereas four of 11 (36 percent) of those episodes in which the vegetation size was 1.0 cm or greater required surgery for persistent pyrexia (p less than 0.05). In all patients requiring surgery, a bioprosthetic tricuspid valve was placed at the time of initial surgery and in no patient did early reinfection occur. This study reconfirms the benign prognosis of right-sided valvular endocarditis. Further, although vegetations of less than 1.0 cm identify those patients who will respond to medical therapy, echocardiographically documented vegetations of 1.0 cm or greater are associated with a significantly lower response rate to appropriate medical therapy. The association of fever that persists for more than three weeks in the absence of another source of infection with an echocardiographically demonstrable right-sided vegetation of 1 cm or more identifies those patients who will require surgical intervention. Finally, tricuspid valve replacement can be performed at the time of initial surgery without undue concern for early reinfection or valve dysfunction.

Adult↗
PubMed1986

Immediate tricuspid valve replacement for endocarditis. Indications and results.

Tricuspid valve excision for tricuspid endocarditis in addicts is recommended to avoid early reinfection, continued sepsis, and late reinfection because of the resumption of intravenous drug abuse. Valvectomy is allegedly well tolerated hemodynamically by some, but it leads to heart failure in at least a third of patients. In our experience in 10 addicts with staphylococcal endocarditis who had failed to respond to antibiotic therapy, tricuspid valve replacement allowed all 10 to leave the hospital free of infection and free of heart failure. Resumption of drug addiction in three led to septic death, but not necessarily to tricuspid reinfection. Two returned to jobs requiring a high level of physical labor and tolerated this without difficulty. We find no need to follow the practice of tricuspid valve excision for tricuspid endocarditis in addicts. Those who refrain from drug abuse are well served by valve replacement. Those who do not are doomed with or without a tricuspid valve.

Acute Disease↗
PubMed1986

Retained intracardiac air. Transesophageal echocardiography for definition of incidence and monitoring removal by improved techniques.

Retained intracardiac air is a continuing hazard for cardiopulmonary bypass. M-mode transesophageal echocardiography of the left atrium, left ventricle, and aorta is a highly sensitive method for detecting retained intracardiac air bubbles. In 15 patients having valve operations and 18 having coronary bypass, M-mode transesophageal echocardiography was used to record air bubbles during and for 15 minutes after bypass. Routine air clearing methods were used: needle aspiration of the ascending aorta (combined coronary and valve operations) and left atrial, left ventricular, and aortic aspiration after careful passive chamber filling (valve operations). Air was detected in 12 of 15 (79%) patients having valve operations and two of 18 (11%) patients having coronary bypass. One with air in the aorta had visible right coronary air embolism. Three patients with positive echograms had transient central nervous system disturbances. In a further 11 patients having valve operations, an ascending aorta-venous shunt was created before bypass was discontinued, but air continued to be present in the left atrium. Finally, in seven patients, we added the following maneuvers to our routine: positive chamber filling with echocardiographic demonstration of left atrial stretching, vigorous chamber ballottement, specific echo-directed chamber aspiration, and maintenance of cardiopulmonary bypass until transesophageal echocardiography showed no retained air. Although small amounts of atrial air could still be detected for a minute or two in some patients, this technique appears finally to have eliminated significant retained air and its consequences. A sensitive technique for intracardiac air detection reveals retained air surprisingly often after cardiopulmonary bypass. There are both possible and probable adverse consequences of this air. After valve operations, it is most difficult to eliminate air from the left atrium. There are three essential elements of air removal: First is mobilization of the air; positive chamber filling, stretching of the atrial wall, and ballottement are critical. Second is removal of mobilized air; continuous ascending aorta-venous shunting and nonsuction venting of the left atrium are very important. Third is proof of elimination of air before cardiopulmonary bypass is terminated; transesophageal echocardiography is vital for this.

Adult↗
PubMed1985

Spurious assessment of acid-base status due to dilutional effect of heparin.

A patient was encountered in whom clinically significant spurious hypocapnia and hypobicarbonatemia were diagnosed resulting from the dilutional effect of excessive amounts of sodium heparin solution in the blood sample. This report presents the relevant data in this patient, summarizes the effects of heparin on the determination of the acid-base status, and provides suggestions for avoiding this important pitfall in clinical practice.

Acid-Base Imbalance↗