Myocardial circulatory and metabolic effects of isoflurane and sufentanil during coronary artery surgery.

The global and regional coronary hemodynamic and myocardial metabolic effects of isoflurane administered intraoperatively as an adjunct to sufentanil were studied in seven of nine patients who experienced increased systemic arterial pressure while undergoing elective coronary artery bypass grafting. All patients were premedicated and maintained on their preoperative medications (beta-blockers, nitrates, Ca++ entry blockers) up to and including the morning of surgery. Systemic and pulmonary hemodynamics and global (coronary sinus, CS) and regional (great cardiac vein, GCV) coronary blood flows were measured, and blood samples were obtained for systemic and myocardial metabolic parameters: after induction with 30 mcg/kg of sufentanil and 0.12 mg/kg vecuronium (FIO2 1.0), but prior to incision (control); 5 min after sternotomy; and during ventilation with isoflurane-oxygen. Heart rate, cardiac output, stroke volume, and GCV/CS flow ratio did not change throughout the study. Neither global nor regional myocardial lactate production was detected in any patient at any time, and the electrocardiogram (lead II, V5) remained unchanged. In response to sternotomy, seven of nine patients experienced an increase in mean systemic arterial pressure of 20% or more (27 +/- 3% from control values), due to an elevation in systemic vascular resistance (30 +/- 5%). Coronary sinus (CS) and great cardiac vein (GCV) flows, as well as CS and GCV lactate extractions, were unchanged 5 min after sternotomy. Both global and regional myocardial oxygen extraction increased, while coronary venous oxygen content decreased. Isoflurane was administered in a dose that restored systemic arterial pressure to baseline values (inspired concentration 0.75-1.0%).(ABSTRACT TRUNCATED AT 250 WORDS)

Quality of life variables in surgical trials.

Clinical trials are commonly performed in surgery to assess the efficacy of one or more treatments. Many therapies result in only partial or temporary improvement, rather than cure. Others sharply affect the quality of patients' lives or of their deaths. For most interventions, it is important to document effects on quality of life as well as morbidity and mortality rates. yet, a review of the literature reveals that very few surgical trials consider quality of life variables as outcome measures. Surgical investigators in areas like cancer, inflammatory bowel disease, end stage renal disease, and cardiac disease have examined quality of life issues extensively using a variety of scales and indices. However, most studies on quality of life are hampered by poor design and inadequate methods of assessment. Failure to evaluate quality of life variables prevents the recognition and full use of potentially beneficial therapies and the rejection of potentially harmful ones.

Electrophysiologic effects on combined autonomic blockade in patients with sinus node disease.

Thirty-two patients were studied before and after i.v. administration of 0.15-0.20 mg/kg of propranolol. Twenty-one of the 32 underwent combined autonomic blockade with the additional infusion of 0.04 mg of atropine. Twenty other patients with sinus node disease underwent electrophysiologic studies both before and after i.v. administration of 0.04 mg of atropine alone. Spontaneous cycle length, maximal corrected sinus node recovery time, sinoatrial conduction time, secondary pauses and intrinsic heart rate were measured. Secondary pauses were more common in those with abnormal intrinsic heart rates, and they did not correlate with changes in maximal corrected sinus node recovery time or sinoatrial conduction time. In patients with normal intrinsic heart rate, abnormal test measurements usually returned to normal after combined blockade (hypervagotonia); however, some patients showed a new abnormality after propranolol that was not reversible with atropine (catecholamine-dependent). Abnormal test responses in patients with abnormal intrinsic heart rate persisted or increased after combined blockade. We conclude that patients with sinus node disease may be categorized as (1) those with intrinsic sinus node disease; (2) those with normal intrinsic sinus node function but either relative hypervagotonia or catecholamine dependency; and (3) those with abnormal intrinsic sinus node function affected by vagal or catecholamine factors.

Long-term vasodilator therapy for heart failure: clinical response and its relationship to hemodynamic measurements.

To assess the clinical efficacy of chronic vasodilator therapy for refractory congestive heart failure, the long-term follow-up (mean 13 months, range 3-30 months) was evaluated in 56 patients treated with hydralazine, usually in combination with nitrates. In the first 6 months, 73% improved subjectively and 59% improved by one or two New York Heart Association classifications; early improvement was usually sustained. Mortality was high, 22% at 6 months and 37% at 12 months, but was significantly lower in patients who had a clinical response to vasodilators (21% in responders vs 55% in nonresponders at 1 year). The only clinical indicator that differentiated responders from nonresponders was the presence or absence of symptomatic progression before initiation of vasodilator therapy. Pulmonary artery pressure, pulmonary capillary wedge (PCW) pressure and stroke work index (SWI) before and during vasodilator therapy correlated with clinical response and survival. Fifteen of 20 patients with PCW < 20 mm Hg and SWI greater than or equal to 30 g-m/m2 improved and survived, compared with two of 19 with PCS greater than or equal to 20 mm Hg and SWI < 30 g-m/m2. Patients who did not have acute hemodynamic improvement generally did not improve clinically, but neither the percentage change nor the absolute change in any hemodynamic variable predicted outcome in the remaining patients. The findings of this study indicate that vasodilators produce clinical improvement in many patients with refractory heart failure and that hemodynamic measurements are helpful in predicting the outcome of therapy.

Electrophysiological effects of disopyramide in patients with bundle branch block.

Electrophysiological studies were performed in 22 patients with intraventricular conduction delay before and after intravenous infusion of disopyramide (Norpace), 2 mg/kg. Mean control maximal sinus node recovery time (1039 +/- 187 msec), atrioventricular nodal conduction time (113 +/- 28 msec), and atrioventricular nodal effective refractory periods (349 +/- 67 msec) did not change significantly after administration of disopyramide (1073 +/- 284 msec, 112 +/- 31 msec, and 342 +/- 42 msec, respectively). Mean spontaneous cycle length (756 +/- 146 msec) decreased significantly 5 minutes after disopyramide (717 +/- 124 msec) (p less than 0.05), but not after 30 minutes (734 +/- 142 msec). A small but statistically significant (p less than 0.05) increase occurred after disopyramide in the mean atrial effective refractory period (259 +/- 51 to 280 +/- 53 msec), ventricular effective refractory period (253 +/- 23 to 275 +/- 33 msec), as well as the relative refractory period of the ventricular specialized conduction system (six patients) 433 +/- 78 to 479 +/- 62 msec). Although mean control infranodal conduction time (67 +/- 35 msec) increased 5 minutes after disopyramide (79 +/- 41 msec) (p less than 0.001) (18%), no spontaneous episodes of second-degree or third-degree atrioventricular block were observed. In six patients with premature ventricular depolarizations (greater than or equal to 1/min), the arrhythmia was totally abolished in four, markedly reduced in one, and remained unchanged in one. Disopyramide resulted in significant prolongation of infranodal conduction time as well as in atrial and ventricular refractoriness, but nevertheless appears to be safe in patients with bundle branch block.

A review of instrumentation and therapeutic techniques in the diagnosis and management of supraventricular tachycardia.

Paroxysmal supraventricular tachycardia can usually be managed without any specific therapy or with an appropriate drug program. Some patients, however, are resistant to conventional therapy. In the past decade, the electrophysiologic pathogenic mechanisms of this rhythm disorder have been elucidated, and this, coupled with progress in intracardiac instrumentation, has enabled the physician to induce specific rhythm disorders and to map them to determine an ideal, specially tailored method of treatment. As a result, the use of radiofrequency pacing and surgery are becoming increasingly important in the treatment of patients with paroxysmal supraventricular tachycardia, especially those with arrhythmias related to Wolff-Parkinson-White syndrome.

Clinical and electrophysiologic findings in patients with paroxysmal slowing of the sinus rate and apparent Mobitz type II atrioventricular block.

Over five years, 13 patients with episodic apparent type II atrioventricular (AV) block associated with sinus slowing were seen. This phenomenon occurred only transiently during an acute illness in eight patients (group I) but recurred chronically in five (groupII). For the group as a whole, the mean spontaneous cycle length was 42% longer during the period of AV block compared with periods of 1:1 AV conduction (800 +/- 116 msec to 1138 +/- 489 msec) (P less than 0.05). Electrophysiologic studies in four group I patients showed no abnormalities, whereas abnormalities in AV nodal conduction and refractoriness or provocation of intranodal Mobitz type II AV block (during carotid massage) were observed in three patients in group II and were totally abolished by atropine. In group I patients, apparent type II AV block was self-limited. In the chronic group, recurrent symptoms required insertion of permanent pacemakers in two patients. Simultaneous type II block and sinus slowing appeared to be related to the effects of increased vagal tone on both nodal structures. Intracardiac pacing is not indicated for patients with transient episodes associated with an acute illness, but may be required for symptomatic patients with recurrent episodes.

Prognostic value of infranodal conduction time in patients with chronic bundle branch block.

His bundle recordings were obtained in 121 patients with chronic bundle branch block and the patients were followed for a mean period of 18 months. Seventy-nine patients had an infranodal conduction time (H-Q) less than 70 msec while 42 had H-Q greater than or equal to 70 msec. There was no significant difference in mean age, smoking history, diabetes, syncope, dizziness, blood pressure, and serum cholesterol or triglyceride levels between the two groups. There was a significantly greater incidence of progresssion to second degree or third degree atrioventricular block (9/42, 21%), and of severe congestive heart failure (16/42, 38%) in patients with H-Q greater than or equal to 70 compared with those with H-Q less than 70 (1/79, 1.3%; and 13/79, 16%, respectively). The risk of sudden death was significantly greater only in the group with H-Q greater than or equal to 70 and severe congestive heart failure. There was no correlation between the presence of first degree atrioventricular block and/or any particular type of bundle branch block pattern with sudden death and/or progression to second degree or third degree atrioventricular block. Analysis of the surface electrocardiogram is only of limited value in predicting high risk patients with chronic bundle branch block. Electrophysiologic studies are of greatest value in patients with bundle branch block with transient neurologic symptoms in whom no cause for the symptoms is evident.