Prinzmetal's angina with coronary artery spasm. Angiographic, pharmacologic, metabolic and radionuclide perfusion studies.

We studied the effects of coronary artery spasm on perfusion of the microvasculature in a patient with Prinzmetal's angina. Intracoronary injections of 99mTc and 131I-labelled macroaggregated human serum albumin were performed (1) at rest, (2) during spontaneous angina, (3) after the administration of nitroglycerin and (4) during pacing-induced spasm and the resultant scans compared. The resting scan was normal. Pain and spasm were associated with a perfusion defect that was localized to the anterior and inferior walls of the left ventricle. The localization of the perfusion defect corresponded with angiographically demonstrated spasm involving left anterior descending and distal circumflex coronary arteries. A subsequent myocardial infarction was localized by 43K scanning to the same perfusion area. Metabolic and parasympathetic stimulation studies were performed but were inconclusive. The patient's recurrent pains were ultimately controlled with large oral doses of isosorbide dinitrate.

Detection of entrapped intracardiac air with intraoperative echocardiography.

Embolization of entrapped intracardiac air represents a significant risk to the patient undergoing open heart surgery. To date, there have been no menas available to ensure that the heart is free of air prior to restoration of the circulation. To assess whether M mode echocardiography can accurately detect intracardiac air, we studied 10 dogs during cardiopulmonary bypass. Randomly, air was or was not injected into the left ventricular cavity of the fibrillating heart. Intracardiac air could be recognized by the presence of a stippled granular pattern, or a loss of the discrete linear echoes or decreased far field echoes, or any combination of these three. In all, 131 random observations were made. When 1.0 cc of air was injected, sensitivity and specificity were both 100 percent, but when 0.2 cc was injected, sensitivity and specificity decreased to 86 and 58 percent, respectively. thus, M mode echocardiography appears to provide a sensitive and specific tool for detecting intracardiac air.

Pneumopericardium following laparoscopy.

There have been no published reports of pneumopericardium complicating laparoscopy. Following an apparently uncomplicated laparoscopy, a 35-year-old woman developed pneumopericardium associated with subcutaneous emphysema of the neck. This resolved without specific therapy and without sequelae.

Long-term results following coronary bypass operation. Importance of preoperative actors and complete revascularization.

The initial 102 patients who underwent aorta-coronary bypass grafting between 1969 and 1971 were followed for a mean of 96 months (minimum follow-up 7 years). Preoperative variables predictive of survival at 5 years were stability of angina, previous heart failure, and left ventricular function. Stability of angina, previous heart failure, previous myocardial infarction, and smoking were important predictors of symptomatic status at 5 years. At operation, 62 patients had anatomic or technically complete revascularization, whereas 40 had incomplete revascularization. There was a significantly improved survival rate in those patients who were completely revascularized. The 5 year survival rate was 84% for completely revascularized patients compared to 96% for incompletely revascularized patient (p less than 0.02). This improvement in survival was continued to 9 years. There was also a significant improvement in asymptomatic status of the completely revascularized patients compared to the incompletely revascularized patients. At 2 years, 75% of the completely revascularized subjects were asymptomatic compared to 45% of the incompletely revascularized patients. However, this difference disappeared after 5 years. Thus complete myocardial revascularization is superior to incomplete revascularization in terms of survival and asymptomatic state. Preoperative variables may be useful in predicting postoperative results.

The elderly patient in the coronary care unit: III. Factors affecting long-term prognosis.

Patients aged 70 years and older who were admitted to a coronary care unit in 1976 with documented acute myocardial infarction were followed to April 30, 1982. At that time, of the 46 patients who had survived initial hospitalization, 28 had died, 16 were still living, and two were lost to follow up. The actuarial survival rates were 71 per cent, 60 per cent, and 44 per cent for one, three, and five years, respectively. Only two of the variables available by history, physical examination, and clinical course of the patient in the coronary care unit had prognostic significance--complex ventricular premature beats and congestive heart failure of any degree of severity. Patients who suffered congestive heart failure during their hospitalization had a five-year survival rate of less than 25 per cent, compared with about 60 per cent for those who had neither heart failure nor complex ventricular premature beats. All five patients who had complex ventricular premature beats died within three years.

The elderly patient in the coronary care unit. I. Acute myocardial infarction.

In a Coronary Care Unit (CCU) with no age barrier for admission, 21 percent of the patients admitted in 1976 were aged 70 or older. Myocardial infarction was documented in 55 of 130 elderly patients. The overall incidence of arrhythmias was similar to that for younger patients. The mean duration of stay in the unit and the CCU mortality (9.1 percent) were similar in both elderly and younger patients, as was the in-hospital mortality rate. Of the patients who survived hospitalization, 75.6 percent were still living 18.1 months after the myocardial infarction. The elderly patient is as likely as the younger one to benefit from admission to a CCU.

The elderly patient in the coronary care unit. II. Incidence and treatment of arrhythmias.

In 1976, 130 patients aged 70 or older were admitted to the Coronary Care Unit (CCU) at Toronto Western Hospital. Arrhythmias were noted in all but 24 percent. Digoxin was given to 53 patients, lidocaine to 24, propranolol to 28, and quinidine to 11. In 2 patients, cardioversion by direct current was required for supraventricular arrhythmias. In 26 patients, temporary pacemakers were used. Of 13 patients who experienced at least one cardiac arrest in the CCU, 10 survived to be discharged to the ward. In total, only 12 of the 130 elderly patients died in the hospital, and in only 3 of these was arrhythmia the primary cause of death. The treatment of arrhythmias in the elderly is as successful and rewarding as in younger patients. Indications for the various antiarrhythmic drugs are similar. Except for digoxin, the dosages of such drugs for the elderly are the same as those for younger patients. Adverse effects apparently are not more common in the elderly.

Surgical procedures involving cardiopulmonary bypass in patients aged 70 or older.

Cardiac surgery was performed in 27 patients whose ages ranged from 70 to 78 years (mean, 72). In 17 of these patients, the operation was coronary artery bypass grafting without other procedures. There were 3 operative deaths (17.6 percent) but no late deaths during a mean follow-up period of 14 months, and all the 14 surviving patients were improved symptomatically. In the other 10 of the 27 patients, the operation was valve replacement. There was no operative mortality among the 6 aortic valve patients and 1 operative death among the 4 mitral valve patients; the corresponding late deaths were 2 and 1, respectively, during a mean follow-up period of 41.3 months. Improvements in operative management and improved criteria for the selection of patients should afford benefits and risks for elderly cardiac patients similar to those for younger cardiac patients.

The cellular electropharmacology of mexiletine combined with sotalol in porcine papillary muscle and Purkinje fibre. I. Alteration of mexiletine-induced Vmax depression.

Using standard microelectrode techniques, the authors compared the effects of 15 to 125 microM concentrations of mexiletine, 31 to 500 microM concentrations of sotalol and 15 to 125 microM of mexiletine combined with 125 microM sotalol, on the beat-to-beat maximum rate of depolarization of phase 0 of the action potential (Vmax) of porcine papillary muscles and Purkinje fibres stimulated by 30 beat trains at a frequency of 1 Hz. Sotalol alone had no effect on Vmax. Mexiletine caused both tonic and use-dependent depression of Vmax in papillary muscle. In the presence of sotalol, tonic Vmax depression was exaggerated, while use-dependent depression was attenuated. In Purkinje fibres, mexiletine exposure resulted in tonic Vmax depression, but no use-dependence could be demonstrated at this frequency. These results are best explained in the context of the modulated receptor hypothesis with the added consideration of two receptors--one within and one external to the sodium channel.

The cellular electropharmacology of mexiletine combined with sotalol in porcine papillary muscle and Purkinje fibre. II. Effects on action potential duration and refractoriness.

Using standard microelectrode techniques, the authors compared the effects of 15 to 125 microM concentrations of mexiletine, 31 to 500 microM concentrations of sotalol and 15 to 125 microM of mexiletine combined with 125 microM sotalol, on the beat-to-beat action potential duration and refractoriness of porcine papillary muscles and Purkinje fibres stimulated by 30 beat trains at a frequency of 1 Hz. Sotalol alone prolonged action potential duration and effective refractory period without altering their ratio. Mexiletine shortened action potential duration while prolonging refractoriness. When the two drugs were combined, action potential duration was shortened to the same extent as with mexiletine alone, but refractoriness, particularly in papillary muscle, was further prolonged. These changes suggest additive inhibition of the sodium window current by both drugs. Purkinje action potential duration was longest in the first beat of the train, while in papillary muscle, this beat was shortest. Exposure to either or both drugs eliminated the prolongation of duration of the first beat of the train in Purkinje fibre. Thus, the phenomenon of restitution, which prolongs the duration of the first beat after a long diastolic interval, appears also to be related to the sodium window current.

The cellular electropharmacology of mexiletine in papillary muscles of guinea pigs chronically treated with amiodarone.

OBJECTIVE: The combination of mexiletine and amiodarone has proved useful in the control of serious ventricular arrhythmias, but the electrophysiological basis for their effectiveness in combination is unknown. The objective of this study was to compare the effects of mexiletine on action potential parameters of papillary muscles taken from guinea pigs chronically treated with amiodarone, with tissue taken from a control group. DESIGN: The effects of 12.5 to 200 microM mexiletine on action potential parameters of papillary muscles taken from guinea pigs chronically treated with amiodarone were compared with tissue taken from a control group, at frequencies of 1.0, 1.5 and 3.0 Hz, using standard microelectrode techniques. Onset of use-dependent block was assessed by 30 beat trains, and recovery from block by extrastimuli at diastolic intervals ranging from 200 to 5000 ms at both 1.5 and 3.0 Hz. ANIMALS: Eighteen four-week-old guinea pigs were randomly divided into two groups. One group received amiodarone in a loading dose of 20 mg/kg/day by intraperitoneal injection for one week, followed by 10 mg/kg/day for 15 weeks. The control animals were given equivalent volumes of dextrose intraperitoneally for 16 weeks. MAIN RESULTS: Mexiletine depressed the maximum rate of depolarization of phase 0 of the action potential (Vmax) in a concentration- and use-dependent fashion. Whereas chronic amiodarone treatment did not alter steady-state Vmax values, the extent of tonic Vmax depression induced by mexiletine was decreased, while use-dependent depression was increased. Mexiletine combined with amiodarone increased effective refractory period prolongation from 306.7 +/- 27.2 to 348.8 +/- 37.2 ms, while action potential duration shortening of mexiletine was moderated from 134.0 +/- 19.8 to 151.0 +/- 8.3 ms (to 90% repolarization at 3 Hz in the presence of 200 microM mexiletine).

Apparent pacemaker malfunction due to ventricular blanking.

Electrocardiographic interpretation in patients with dual chamber pacemakers requires an intimate understanding of their manner of functioning. This report describes a patient whose pacemaker was suspected of malfunction because of failure to sense premature beats. This sense-failure resulted from the fortuitous concurrence of the sensed portion of the premature beat with the ventricular blanking period and was resolved by reducing the low rate limit of the pacemaker. Three principles must be recognized in interpreting suspected failure of sensing: 1. The channel of origin of the pacing artifact must be identified. 2. The surface QRS morphology does not necessarily correspond to the signal detected by the pacemaker. 3. Failure to sense does not necessarily equal pacemaker malfunction.

Interactions between a rapid atrial stimulator and a multiprogrammable ventricular demand pacemaker.

A patient with drug-resistant supraventricular tachycardia was well controlled for 8 years with a patient-activated rapid atrial pacemaker until she developed symptomatic bradycardic episodes. A multiprogrammable ventricular pacemaker was implanted. Assessment of the interactions between the two pacemakers demonstrated inhibition of VVI pacing by the atrial stimulator initially. Two months after implant no interaction was seen. At no time was VVT pacing affected by the atrial stimulator. Thus, interactions between these two units can occur and a multiprogrammable pacemaker should be used in this situation as it offers the flexibility to minimize any interaction that might be present.

Antiarrhythmic therapy in the elderly: pacemakers and drugs.

Investigations of syncope often fail to demonstrate any abnormality. However, in view of the ease of permanent pacemaker implantation and the potential dangers of recurrent syncope, patients with this symptom should receive pacemaker therapy. In general, acute therapy of any tachyarrhythmia associated with hemodynamic collapse consists of DC cardioversion, but skillful use of drug therapy and, occasionally, pacemaking are also highly important in preventing recurrences.

A simple BASIC program for constructing three-dimensional graphs.

This report describes a simple program for plotting three-dimensional curves and thus allowing a visual representation of the simultaneous interaction of three variables. Graphs can be displayed on the screen or printed using a graphics printer. The original data can be stored, printed, recalled and edited, as can the graph parameters. Completed graphs can also be stored for later review or printing. The program as outlined can accommodate up to 10 curves of up to 50 points each, but these limits can be easily increased. The program is written in BASIC, thus allowing it to be readily modified. As listed, the complete source code has 357 lines and occupies about 12 kilobytes when saved in compressed binary format.

Permanent pacemaker malfunction: diagnostic aspects of temporary pacing.

A temporary pacing electrode can function as a diagnostic as well as a therapeutic tool. This is illustrated in two patients whose permanent pacemakers unexpectedly failed. In the first patient a demand pacemaker was inhibited by a magnet rather than converting to the asynchronous mode. In the second the pacemaker appeared to be producing low-voltage potentials not detectable on the surface electrocardiogram. The presence of a temporary pacing electrode can be useful for defining the cause of pacemaker failure and the nature of any associated arrhythmias.

The surface electrocardiogram in complete intra-his heart block.

In some cases, the surface ECG may be useful in predicting that the level of heart block is intra-His rather than supra-His. In five patients with third degree heart block the level of block was documented to be within the His bundle. In all five, the surface ECG showed an escape rhythm with QRS complexes of less than 0.10s. duration. The initial QRS forces were abnormal in that "septal" q waves were not present in leads 1 and V6. Two of the five patients had occasional conducted beats with normal "septal" q waves. Thus, heart block associated with an escape rhythm of narrow QRS morphology but abnormal septal depolarization may indicate that the level of the block is intra-His rather than supra-His.