Charles A. Sanders

Myocardial Changes Associated with Cardiogenic Shock

Abstract The amount of left ventricular myocardium destroyed by recent and old infarcts in patients with acute myocardial infarction with and without cardiogenic shock was compared in hearts obtained at autopsy. All 20 patients with, and only one of 14 without, shock had lost 40 per cent or more of the left ventricle. The remainder lost 35 per cent or less. These results indicate that cardiogenic shock is associated with extensive loss of left ventricular myocardium due to new and frequently old infarcts as well. In five cases the new infarct was small as compared to the total amount of myocardial destruction. Patients with cardiogenic shock consistently showed marginal extension of the recent infarct (unlike those not in shock) and focal areas of necrosis throughout both left and right ventricles. Similar focal lesions were encountered in a third series of 20 patients with shock from other causes. A sharp reduction in coronary perfusion pressure could explain this combination of findings, which indicate ...

Use of Sublingual Nitroglycerin in Congestive Failure following Acute Myocardial Infarction

The effect of 0.3 mg sublingual nitroglycerin (NTG) was evaluated by hemodynamic measurements and precordial S-T-segment mapping in 17 patients following acute myocardial infarction.In all cases NTG produced a prompt reduction in mean pulmonary capillary wedge pressure (PCW) from an average of 19 ± 2 to 14 ± 1 mm Hg associated with a small fall in mean arterial pressure from a mean of 85 ± 4 to 82 ± 4 mm Hg. No significant change in heart rate occurred.In patients without left ventricular failure (PCW 3-12 mm Hg) cardiac output (CO) fell 9%. By contrast, in patients with moderate left ventricular failure (PCW 13-22 mm Hg) CO rose 18%. In three patients with refractory left ventricular failure (PCW 25-31 mm Hg) CO rose 25%. Two of these patients were treated with repetitive NTG doses in addition to previously ineffective diuretic therapy with resolution of resistant pulmonary edema. No significant changes in the magnitude of S-T-segment elevations were noted.NTG may have a special role in the management of acutely ill patients with myocardial infarction in whom pulmonary edema does not respond to conventional therapy.

Clinical and Hemodynamic Results of Intraaortic Balloon Pumping and Surgery for Cardiogenic Shock

The AVCO balloon pump has been employed in treating 40 patients with cardiogenic shock from acute myocardial infarction (CS-MI). All patients were given a trial of medical therapy with hemodynamic monitoring. The time from the development of shock to institution of intraaortic balloon pumping (IABP) was less than 24 hours in all but nine patients. Prior to IABP the mean hemodynamic values were: cardiac index (CI) 1.7 liters/min/m2; mean arterial pressure (MAP) 66 mm Hg; pulmonary artery wedge pressure (PAW) 22 mm Hg. After 24-48 hours of IABP the CI and MAP had increased 0.8 liters/min/m2 and 8 mm Hg, respectively, and the PAW had decreased 4.8 mm Hg. During IABP the shock syndrome was reversed in 31 patients. Four of 25 patients treated with IABP alone survived to be discharged, but two have died from subsequent infarctions. Because of the persistent high mortality, 15 patients judged unable to survive off IABP have undergone emergency surgical procedures with IABP continuing during preoperative angiography and postoperatively. Six were long-term survivors. It is concluded: (1) IABP is a safe, effective means of supporting the circulation in CS-MI; (2) IABP alone will improve survival in some patients; (3) IABP can provide circulatory support during angiography and the perioperative period in patients requiring revascularization for survival; and (4) some patients with CS-MI have myocardial necrosis too extensive to permit survival without permanent circulatory assistance or total cardiac replacement.

Autopsy Findings with Permanent Pervenous Pacemakers

Of 130 patients who received permanent pervenous pacemakers in the last 2 years at the Massachusetts General Hospital, 21 have died; complete postmortem data are available on seven who died 5 days to 18 months after insertion of the pacemaker. No deaths were related to pacemaker malfunction. No patient received routine anticoagulant therapy. The intracardiac portions of all pacemaker electrodes were 30 to 80% endothelialized. In three cases tiny, organized mural thrombi formed on these sheaths, but none appeared to give rise to pulmonary emboli. All pacemaker electrode tips were wedged firmly beneath the trabecular system of the right ventricular apex and elicited varying degrees of local fibrous tissue reaction. Further focal fibrotic attachments occurred in the right atrium and superior vena cava. Although in four cases the electrodes adhered to the chordae tendineae, the long-term presence of an electrode did not appear to compromise tricuspid valve function. Late removal of an electrode may be hazardous because of its firm attachments to the endocardium and tricuspid valve.

Improvement in Myocardial Function and Coronary Blood Flow in Ischemic Myocardium after Mannitol

The purpose of this study was to evaluate the effect of hyperosmolality on the performance of, and the collateral blood flow to, ischemic myocardium. The myocardial response to mannitol, a hyperosmolar agent which remains extracellular, was evaluated in anesthetized dogs. Mannitol was infused into the aortic roots of 31 isovolumic hearts and of 15 dogs on right heart bypass, before and during ischemia. Myocardial ischemia was produced by temporary ligation of either the proximal or mid-left anterior descending coronary artery. Mannitol significantly improved the depressed ventricular function curves which occurred with left anterior descending coronary artery occlusion. Mannitol also significantly lessened the S-T segment elevation (epicardial electrocardiogram) occurring during myocardial ischemia in the isovolumic hearts and this reduction was associated with significant increases in total coronary blood flow (P < 0.005) and with increased collateral coronary blood flow to the ischemia area (P < 0.005).THUS, INCREASES IN SERUM OSMOLALITY PRODUCED BY MANNITOL RESULT IN THE FOLLOWING BENEFICIAL CHANGES DURING MYOCARDIAL ISCHEMIA: (a) improved myocardial function, (b) reduced S-T segment elevation, (c) increased total coronary blood flow, and (d) increased collateral coronary blood flow.

Effects of Intra-Aortic Balloon Counterpulsation on Cardiac Performance, Oxygen Consumption, and Coronary Blood Flow in Dogs

The effect of intra-aortic Counterpulsation (IACP) with a balloon upon myocardial oxygen consumption (MV·o2), coronary blood flow (TCF), and left ventricular performance was studied in 23 anesthetized canine right heart bypass preparations at constant heart rate and cardiac output. In nonhypotensive, nonTCF-limited preparations, IACP produced a fall in left ventricular peak systolic pressure (LVP) and a decrease in MV·o2 (-1.1 ± 0.2 (SE) ml/min/100 g LV). In these animals there was little steady state change in TCF (-5.6±5.9 ml/min), secondary to autoregulation by the coronary vascular bed. Left ventricular end-diastolic pressure (LVEDP) fell if elevated but exhibited little change if initially normal. However, in hypotensive preparations, in which left ventricular performance was substantially limited by a decreased TCF, IACP produced a striking increase in TCF (+40.9 ± 8.6 ml/min) accompanied by an increase in MV·o2 (+1.2±0.3 ml/min/100 g LV). Elevated LVEDPs fell substantially toward normal. Directiona...

Intraaortic balloon pumping for ventricular septal defect or mitral regurgitation complicating acute myocardial infarction.

The intraaortic balloon pump (IABP) has been employed in the management of five patients with ventricular septal rupture (VSD) and six patients with acute mitral regurgitation (AMR) following myocardial infarction. All patients were in cardiogenic shock which responded poorly to medical therapy including pressor and inotropic agents. IABP resulted in significant clinical and hemodynamic improvement in all cases.In patients with VSD, IABP produced a fall in wedge (PCW) pressure from 17 ± 4 (SD) to 13 ± 4 mm Hg (P < 0.01) while mean arterial pressure increased from 68 to 73 mm Hg. Systemic A-V O2 difference fell from 9.7 ± 2.4 to 8.1 ± 2.4 vol % (P < 0.05) while pulmonary A-V O2 difference was unchanged. Thus the pulmonic/systemic flow ratio (P/S) declined in all patients. In patients with AMR, PCW fell from 25 ± 4 to 20 ± 4 mm Hg (P < 0.02) with a significant diminution in “V”-wave amplitude. Cardiac output (CO) rose from 3.1 ± 0.9 to 3.7 ± 1.0 liters/min (P < 0.01). All patients underwent coronary angiography without complication in preparation for emergency surgery.IABP reduces AMR following acute myocardial infarction and reduces the P/S in VSD by a selective augmentation of systemic CO. Such direct therapy acutely stabilizes these severely ill patients. Detailed angiography may then be performed safely.

Sequential Atrioventricular Pacing in Heart Block Complicating Acute Myocardial Infarction

Abstract The hemodynamic effects of ventricular pacing and of sequential atrioventricular pacing were compared in nine patients with second-degree or third-degree heart block complicating acute myocardial infarction. The restoration of normal atrioventricular relations resulted in an increase in cardiac output in each case (average values of 2.9 to 3.6 liters per minute, or 24 per cent — p less than 0.001). Significant rises in arterial pressure and falls in venous pressure were also obtained. Because of the small number of cases and the short study period, the overall clinical effect of sequential pacing could not be assessed, nor could an opinion be formed concerning its effect on prognosis.

Role of Renin in Acute Postural Homeostasis

Plasma renin activity has been measured by radioimmunoassay at frequent intervals after passive upright tilting and correlated with pulse and blood pressure in normotensive man. In the normal response to upright posture, renin activity in both peripheral and renal veins increases consistently within a few minutes. The renin rise lags behind the increase in pulse rate and diastolic blood pressure. Renin activity falls to base-line level soon after return to the horizontal position. In the 25% of normal subjects who develop vasovagal syncope after upright tilting, the increase in renin activity is smaller in magnitude and duration than in the normal response. Renin levels fall just before syncope appears and rise sharply after return to the horizontal position. Anephric patients are able to effect adequate postural adjustments even in the absence of renin activity.This study indicates that the renin angiotensin system participates in the acute response to postural change in normal man and that it functions abnormally in vasovagal syncope.

A comparison of the hemodynamic effects of ventricular and sequential A-V pacing in patients with heart block☆

Abstract A comparison was made of the effects of ventricular pacing and sequential A-V pacing at individually determined optimal P-R intervals in ten patients with A-V block. At heart rates 10 beats per minute faster than sinus rate, the average cardiac output increased from 4.6 to 5.7 L. per minute (24 per cent, p