Acute and chronic hypothyroidism are associated with similar left ventricular diastolic dysfunction relative to the euthyroid state: results of doppler echocardiographic comparisons.

BACKGROUND: How the duration of hypothyroidism affects left ventricular diastolic function is not well-characterized. AIM: We sought to compare left ventricular diastolic function in acutely vs chronically hypothyroid patients vs euthyroid controls, and within individuals while on vs off T4. SUBJECTS AND METHODS: We prospectively performed such comparisons measuring pulsed-wave and color M-mode Doppler echocardiographic variables: early or late mitral peak velocities (E wave or A wave, respectively), E wave/A wave ratio, E wave deceleration time, isovolumic relaxation time (IVRT), mitral flow propagation velocity (Vp), E wave/Vp ratio. Subjects comprised the acute HYPO group, 10 patients undergoing T4 withdrawal ≥ 6 months post-primary treatment for differentiated thyroid cancer (DTC); the chronic HYPO group, 23 treatment-naïve Hashimoto thyroiditis patients; and 21 healthy euthyroid controls. Subjects were adults aged ≤ 60 yr, predominantly female, with sinus rhythm; exclusion criteria were cardiovascular or thyroid disorder besides DTC (Hashimoto thyroiditis) in acute (chronic) HYPO patients or medication (besides thyroid hormone) affecting cardiac or thyroid function. RESULTS: Mean IVRT was significantly delayed and mean Vp, significantly slowed in both HYPO groups vs controls (p<0.0005), but did not differ between HYPO groups. These variables also were significantly impaired (p<0.05) within individuals when off vs on T4 (no.=8 acute, 10 chronic HYPO patients). Both HYPO groups had elevated mean E wave/Vp ratios vs controls, but the elevation reached significance (p<0.05) only in the larger chronic HYPO group. CONCLUSIONS: Left ventricular diastolic dysfunction is largely similar in acutely or chronically hypothyroid patients off T4 vs healthy controls or the same patients on T4.

The hyperventilation test as a method for developing successful therapy in Prinzmetal's angina.

In 10 cases of Prinzmetal's angina in which episodes of myocardial ischemia were easily and reproducibly induced by hyperventilation, this test was performed 111 times, 41 times under control conditions and 70 times during treatment with one or more of the following drugs: phentolamine, isosorbide dinitrate, propranolol, verapamil, nifedipine and amiodarone. Seventeen of 18 negative tests performed under the influence of a long-acting drug coincided with total remission of the patient's anginal episodes when this drug was administered on a short- or long-term basis. No patient died or sustained infarction during a follow-up period of 10.9 months. A negative test was thus a good indication that the clinical response to the corresponding drug would be favorable. The electrocardiographic changes and chest pain provoked by hyperventilation occurred not when alkalosis was greatest (hydrogen ion [pH] change from 7.42 to 7.58, p less than 0.001), but when pH was approaching normal or control values. The onset of electrocardiographic changes occurred an average of 175 seconds after the end of hyperventilation and, in two cases, the time lag was as much as 480 and 705 seconds, respectively. This raises several questions regarding the true mechanism triggering coronary spasm under such conditions. The hyperventilation test appears to be a useful and safe procedure for selecting the best possible drug for long-term treatment of Prinzmetal's angina as well as for comparing the relative efficacy of different drugs.

Long-term management of sustained, recurrent, symptomatic ventricular tachycardia with amiodarone.

Twenty-three patients with sustained, recurrent, symptomatic ventricular tachycardia were treated with oral amiodarone. Initial doses were 600-2000 mg/day and maintenance doses were 200-1200 mg/day. Amiodarone was highly effective in 20 patients (87%), seven of whom had a follow-up of 30 months or longer, including two who were followed for 5 years. Three patients died within the first 45 days, three died suddenly after a follow-up of 33.5 months, and four had a nonarrhythmic death after a follow-up of 25 months. Fifteen patients (65%) had no recurrence during a follow-up of 21.5 months, while five (22%) had isolated recurrences during a follow-up of 32.2 months. The average maintenance dose was 713 mg/day in the 15 patients who did not have recurrences and 375 mg/day in the five patients who had recurrences (p less than 0.001). Both short- and long-term tolerance were excellent and there was not a single case in which treatment had to be discontinued. The main disadvantage of amiodarone was that it took an average of 9.5 days to reach anti-arrhythmic efficacy. The main advantages were prolonged duration of action (recurrences occurred only 15-60 days after the drug was discontinued or the dose lowered, virtual absence of contraindications, doses as high as 2000 mg/day were safe and patient compliance was excellent.