Heart rate reduction

Nitrates have been suggested in patients who do not achieve therapeutic goals (heart rate reduction) with P-blocker therapy alone. Trials to evaluate the effects of nitrates (e.g., isosorbide mononitrate) on portal pressure, both alone and in combination with P-blockers, show enhanced reduction of portal pressure however, there is an increase in mortality when nitrates are used alone. Adverse effects are significantly higher in patients treated with the combination of non-selective P-blockers and nitrates as opposed to P-blocker monotherapy.42,43 Unfortunately,... 

Assess the effectiveness of (3-blocker therapy by measuring heart rate. Heart rate reduction of 25% from baseline or to 55 to 60 beats/minute is desirable. Ask the patient specific, directed questions regarding adverse effects of p-blockers inquire about symptoms of orthostatic hypotension (e.g., lightheadedness, dizziness, or fainting). 

Mulder P, Barbier S, Chagraoui A, et al. Long-term heart rate reduction induced by the selective 1(f) current inhibitor ivabradine improves left ventricular function and intrinsic myocardial structure in congestive heart failure. Circulation 1674 109 1674-9. 

Reduction in blood pressure Reduction in cardiac contractile force Reduction in heart rate Reduction in heart size... 

Dlltlazem (Cardizem) Less pronounced heart rate reduction. Reduces afterload by dilating peripheral arteries. Increases oxygen supply to myocardium by preventing sympathetic -induced coronaiy artery spasm. Reduces angina episodes. Increases exercise tolerance in stable angina. Also used as an antihypertensive. Edema, headache, dizziness, asthenia, nausea, rash. 

In a single-dose, placebo-controlled, crossover study in 16 healthy men, bisoprolol 5 mg given with imidapril 10 mg did not significantly influence the pharmacokinetics of its active metabolite imidaprilat, and the pharmacodynamic effects, including blood pressure and heart rate reductions, were mainly additive. ... 

A study found that ketoconazole 200 mg daily or josamycin 1 g twice daily increased ivabradine plasma levels by seven to eightfold. Studies in healthy subjects given diltiazem or verapamil have resulted in an increase in the AUC of ivabradine of two to threefold, and an additional heart rate reduction of 5 bpm. ... 

The manufacturers advise that ivabradine should not be taken with drugs that prolong the QT interval. Bradycardia is a pharmacological effect of ivabradine, and QT prolongation may be exacerbated by heart rate reductions. For a list of drugs known to affect the QT interval see Table 9.2 , (p.257). 

In a randomised, double-blind, placebo-controlled study in 12 healthy subjects, phenelzine 15 mg three times daily for 7 days had no effect on the dose of intravenous noradrenaline (norepinephrine) required to raise the systolic blood pressure by 25 mmHg. In addition, phenelzine had no effect on the diastolic blood pressure rises and heart rate reductions seen with noradrenaline. In this study, phenelzine itself had no effect on blood pressure or heart rate. Similarly, in an earlier study in two healthy subjects given phenelzine 15 mg three times daily and two given tranylcypromine 10 mg three times daily for 7 days, there was no signifieant... 

A 45-year-old Japanese woman with multiple sclerosis taking tizanidine 3 mg daily had a reduction in blood pressure (from 124/88 to 102/74 mniHg) and heart rate (from 86 to 58 bpm) shortly after starting to take ciprofloxacin 400 mg daily. After 2 days she complained of drowsiness and her blood pressure was 92/54 mmHg. Retrospective analysis revealed 8 patients who had received tizanidine and ciprofloxacin concurrently. In these patients, the mean reduction in blood pressure on starting ciprofloxacin was 21.3/15.4 mmHg, and the heart rate reduction was 14.9 bpm. Adverse effects attributable to tizanidine occurred in three of the patients. ... 

Because of these still-existing limitations, further CT scanner technology developments ensued. As a result, the dual-source 64-sHce CT scaimer was introduced. This CT system offers a high temporal resolution of 83 ms in a monosegment reconstruction mode, which has dispensed the necessity for administering P-blocking medication for heart rate reduction prior to CT coronary angiography (Achenbach et al. 2006 Johnson et al. 2006 Scheffel et al. 2006). 

ACE inhibitors lower the elevated blood pressure in humans with a concomitant decrease in total peripheral resistance. Cardiac output is increased or unchanged heart rate is unchanged urinary sodium excretion is unchanged and potassium excretion is decreased. ACE inhibitors promote reduction of left ventricular hypertrophy. 

P-Adrenoceptor Blockers. There is no satisfactory mechanism to explain the antihypertensive activity of P-adrenoceptor blockers (see Table 1) in humans particularly after chronic treatment (228,231—233). Reductions in heart rate correlate well with decreases in blood pressure and this may be an important mechanism. Other proposed mechanisms include reduction in PRA, reduction in cardiac output, and a central action. However, pindolol produces an antihypertensive effect without lowering PRA. In long-term treatment, the cardiac output is restored despite the decrease in arterial blood pressure and total peripheral resistance. Atenolol (Table 1), which does not penetrate into the brain is an efficacious antihypertensive agent. In short-term treatment, the blood flow to most organs (except the brain) is reduced and the total peripheral resistance may increase. 

Intoxication with amyl nitrite or butyl nitrite (i.e., poppers) is characterized by euphoria, warm feelings, change in perception of time, a sense of fullness in the head, relaxation of smooth muscle, vasodilatation, increased heart rate, and decreased systolic blood pressure. An increase in sexual drive and intensification of orgasm, poor judgment, and a reduction in inhibitions are... 

Intravenous or oral doses of a P-blocker should be administered early in the care of a patient with STE ACS, and then oral agents should be continued indefinitely. Early administration of a P-blocker to patients lacking a contraindication within the first 24 hours of hospitalization is a quality care indicator.2,3 In ACS the benefit of P-blockers mainly results from the competitive blockade of P,-adrenergic receptors located on the myocardium. Pi-Blockade produces a reduction in heart rate, myocardial contractility, and blood pressure, decreasing myocardial oxygen demand. As a result of these effects, P-blockers reduce the risk for recurrent ischemia, increase in infarct size and risk of reinfarction, and occurrence of ventricular arrhythmias in the hours and days following MI.39... 

Monitor for improvement of symptoms in patients with active IBD, such as reduction in the number of daily stools, abdominal pain, fever, and heart rate. 

Doses should be titrated as tolerated with the goal of decreasing heart rate by 25% or to approximately 55 to 60 beats/minute.11,36 Heart rate is not an accurate marker for portal pressure reduction, but it is the accepted surrogate marker for effectiveness because there are no other acceptable alternatives. 

The answer is F. (Katzung, p 167, Hardman, pp 237-2382 Labetalol has potent a and p antagonist actions, due to the specific components of its racemic mixture of four isomeric compounds. Cardiac output and heart rate change minimally, while blood pressure decreases due to a overall reduction in peripheral resistance. The combined a and p antagonism has been found to be of advantage in treating pheochromocytomas. 

Common carp, Cyprinus carpio recently-fertilized eggs exposed to 25-186 pg/L at pH 7.5 or 5.6 Lake trout, Salvelinus namaycush At pH 7.5, lead increased heart rate and decreased body movements. At pH 5.6 there was a dose-dependent reduction in survival and increase in spinal cord deformities 42... 

---