Bioeffects of albumin-encapsulated microbubbles and real-time myocardial contrast echocardiography in an experimental canine model

Myocardial contrast echocardiography has been used for assessing myocardial perfusion. Some concerns regarding its safety still remain, mainly regarding the induction of microvascular alterations. We sought to determine the bioeffects of microbubbles and real-time myocardial contrast echocardiography (RTMCE) in a closed-chest canine model. Eighteen mongrel dogs were randomly assigned to two groups. Nine were submitted to continuous intravenous infusion of perfluorocarbon-exposed sonicated dextrose albumin (PESDA) plus continuous imaging using power pulse inversion RTMCE for 180 min, associated with manually deflagrated high-mechanical index impulses. The control group consisted of 3 dogs submitted to continuous imaging using RTMCE without PESDA, 3 dogs received PESDA alone, and 3 dogs were sham-operated. Hemodynamics and cardiac rhythm were monitored continuously. Histological analysis was performed on cardiac and pulmonary tissues. No hemodynamic changes or cardiac arrhythmias were observed in any group. Normal left ventricular ejection fraction and myocardial perfusion were maintained throughout the protocol. Frequency of mild and focal microhemorrhage areas in myocardial and pulmonary tissue was similar in PESDA plus RTMCE and control groups. The percentages of positive microscopical fields in the myocardium were 0.4 and 0.7 percent (P = NS) in the PESDA plus RTMCE and control groups, respectively, and in the lungs they were 2.1 and 1.1 percent, respectively (P = NS). In this canine model, myocardial perfusion imaging obtained with PESDA and RTMCE was safe, with no alteration in cardiac rhythm or left ventricular function. Mild and focal myocardial and pulmonary microhemorrhages were observed in both groups, and may be attributed to surgical tissue manipulation.

L-arginine reduces heart rate and improves hemodynamics in severe congestive heart failure.

BACKGROUND: Stimulated endothelium-derived relaxing factor-mediated vasodilation and conduit artery distensibility are impaired in congestive heart failure (CHF). L-arginine could have a potentially beneficial role in CHF, acting through the nitric oxide (NO)-L-arginine pathway or by growth hormone increment. HYPOTHESIS: This study was undertaken to investigate the effects of L-arginine on heart rate, hemodynamics, and left ventricular (LV) function in CHF. METHODS: In seven patients (aged 39 +/- 8 years) with CHF, we obtained the following parameters using echocardiography and an LV Millar Mikro-Tip catheter simultaneously under four conditions: basal, during NO inhalation (40 ppm), in basal condition before L-arginine infusion, and after L-arginine intravenous infusion (mean dose 30.4 +/- 1.9 g). RESULTS: Nitric oxide inhalation increased pulmonary capillary wedge pressure from 25 +/- 9 to 31 +/- 7 mmHg (p < 0.05), but did not change echocardiographic variables or LV contractility by elastance determination. L-arginine decreased heart rate (from 88 +/- 15 to 80 +/- 16 beats/min, p<0.005), mean systemic arterial pressure (from 84 +/- 17 to 70 +/- 18 mmHg, p < 0.007), and systemic vascular resistance (from 24 +/- 8 to 15 +/- 6 Wood units, p<0.003). L-arginine increased right atrial pressure (from 7 +/- 2 to 10 +/- 3 mmHg, p<0.04), cardiac output (from 3.4 +/- 0.7 to 4.1 +/- 0.8 l/min, p < 0.009), and stroke volume (from 40 +/- 9 to 54 +/- 14 ml, p < 0.008). The ratios of pulmonary vascular resistance to systemic vascular resistance at baseline and during NO inhalation were 0.09 and 0.075, respectively, and with L-arginine this increased from 0.09 to 0.12. CONCLUSION: L-arginine exerted no effect on contractility; however, by acting on systemic vascular resistance it improved cardiac performance. L-arginine showed a negative chronotropic effect. The possible beneficial effect of L-arginine on reversing endothelial dysfunction in CHF without changing LV contractility should be the subject of further investigations.

[Drug treatment for stable coronary artery disease at primary and tertiary medical centers]. / Tratamento medicamentoso da doença arterial coronária estável em centros de atendimento primário e terciário.

PURPOSE: To observe the distribution of the main drugs used in patients with stable coronary heart disease, in primary and tertiary medical care centers (MCC). METHODS: We studied 300 consecutive out patients at the Hetat Institute with the diagnosis of stable coronary artery disease, 205 (68%) males and 95 (32%) female, aged from 31 to 80 (mean 58 +/- 8.0) years old. Drug intake was evaluated. RESULTS: We observed that the use of nitrates (48% vs 55%; p = NS) and calcium antagonists (46% vs 37%; p = NS), respectively in both primary and tertiary MCC was similar. The beta blockers were used more often in the primary MCC (50% vs 35%; p = 0.02). Angiotensin converting enzyme inhibitors (11% vs 42%; p < 0.001), diuretics (30% vs 49%; p = 0.002) and aspirin (44% vs 76%; p = 0.0001) were more frequently used in the tertiary MCC. CONCLUSION: We observed similar frequency of use of nitrates and calcium antagonists in both centers. There was a higher use of beta blockers in primary MCC. The angiotensin converting enzyme inhibitors and antiplatelet agents were more used in the tertiary MCC. In relation to the updated literature, the best pharmacotherapy to coronary artery disease should be optimized in both centers.

Efeitos eletrocardiográficos e hemodinâmicos do cloridrato de amiodarona por via venosa / Electrocardiographic and hemodynamic effects of amiodarone hydrochloride by intravenous route

Quatorze pacientes portadores de cardiomiopatia chagasica cronica, com arritmias ventriculares persistentes e insuficiencia miocardica, foram submetidos a avaliacao eletrocardiografica continua por periodo de 24 horas (em 12 pacientes) e a estudo hemodinamico, antes (condicao de controle) e apos (condicao 20, 40 e 60 minutos) a administracao de 5 mg/kg de peso seguida por infusao venosa continua de 900 a 1050 mg de cloridrato de amiodarona (AM) por periodo de 24 horas. Houve reducao porcentual media de 73,5% no numero de extra-sistoles ventriculares sem modificacoes apreciaveis nos episodios de taquicardia ventricular. Entre as condicoes 20 e 60 minutos, ocorreu diminuicao significativa da frequencia cardiaca (FC) e do indice cardiacao e aumento nas pressoes media do atrio direito (AD), na diastolica final do ventriculo esquerdo e nas resistencias arterial pulmonar e vascular sistemica. Com excecao dos valores da FC e da AD, as demais variaveis hemodinamicas retornaram aos valores de controle 24 horas a infusao venosa continua de AM. Em vista da depressao da funcao cardiaca que persistiu ate 60 minutos, concluiu-se que o AM deve ser cuidadosamente administrado principalmente em pacientes con insuficiencia miocardica