Transdermal nitroglycerin patch therapy improves left ventricular function and prevents remodeling after acute myocardial infarction: results of a multicenter prospective randomized, double-blind, placebo-controlled trial

BACKGROUND

Nitrates are widely used in the treatment of angina in patients with acute myocardial infarction (AMI). Short-term administration prevents left ventricular (LV) dilation and infarct expansion. However, little information is available regarding their long-term effects on LV remodeling in patients surviving Q-wave AMI.

METHODS AND RESULTS

This was a randomized, double-blind, placebo-controlled trial designed to investigate the long-term (6-month) efficacy of intermittent transdermal nitroglycerin (NTG) patches on LV remodeling in 291 survivors of AMI. Patients meeting entry criteria had baseline gated radionuclide angiography (RNA) followed by randomization to placebo or active NTG patches delivering 0.4-, 0.8-, or 1.6-mg/h. RNA was repeated at 6 months and 6.5 days after withdrawal of double-blind medication. The primary study end point was the change in end-systolic volume index (ESVI). Both ESVI and end-diastolic volume index (EDVI) were significantly reduced with 0.4-mg/h NTG patches (-11.4 and -11.6 mL/m2, respectively, P<.03). This beneficial effect was observed primarily in patients with a baseline LV ejection fraction < or =40% (deltaESVI, -31 mL/m2; deltaEDVI, -33 mL/m2; both P<.05) and only at the 0.4-mg/h dose. After NTG patch withdrawal, ESVI significantly increased but did not reach pretreatment values.

CONCLUSIONS

Transdermal NTG patches prevent LV dilation in patients surviving AMI. The beneficial effects are limited to patients with depressed LV function and only at the lowest (0.4-mg/h) dose. Continued administration is necessary to maintain efficacy. Whether these remodeling effects confer a clinical or survival advantage will need to be addressed in an adequately powered cardiac event trial.

Acoustical factors of noise created by suctioning middle ear fluid

OBJECTIVE

To quantify the intensity, spectral content, and duration of exposure for suction noise created during aspiration of middle ear fluid following myringotomy.

DESIGN

Case series.

SETTING

Tertiary care center.

PATIENTS OR OTHER PARTICIPANTS

Convenience sample of 245 myringotomies performed on 124 patients ranging in age from 6 months to 14 years (mean age, 2 years 8 months).

MAIN OUTCOME MEASURES

Intensity, spectral content, and duration of exposure associated with suction noise were defined by electroacoustic analysis of high-fidelity tape recordings of the noise created during suctioning middle ear fluid.

RESULTS

The intensity of suction noise ranged from 74 to 117 dB; most acoustic energy was concentrated in the frequency range between 1.7 and 6.0 kHz, and the duration of exposure varied from 4 to 23 seconds.

Hair cell loss and regeneration after exposure to intense sound in neonatal chicks

Neonatal chicks (between 1 and 3 days of age) were exposed to an intense pure tone for 48 hours, then killed immediately after removal from the sound, or 14 days later. Nonexposed age-matched animals served as controls. The inner ear was removed and the auditory receptor organ (the basilar papilla) was prepared for evaluation by scanning electron microscopy. The site of injury on the papilla was described in terms of hair-cell loss and location. The ears with no recovery showed a discrete lesion area, within which there was complete disruption of the hair-cell field and a 35% loss in hair cells. After 14 days' recovery, no hair cell loss could be detected, though the lesion could still be recognized by the disorganization of hair cells in the previously injured area. These data demonstrate hair-cell restoration after severe acoustic injury from intense sound exposure in the neonatal ear.